After holding forth on the Senate floor for almost 13 hours, Kentucky Republican Sen. Rand Paul has ended a lengthy filibuster of the president's nominee to lead the CIA. 

Paul, who cited objections over the administration's policy regarding potential drone attacks on U.S. citizens, relinquished the Senate floor at nearly 1 a.m. ET early Thursday morning. 

In the end, it was nature that called. 

"I've discovered that there are some limits to filibustering, and I am going to have to take care of one of those in a few minutes here," he said to laughter after thanking his supporters and staff. 

Forcing the question of civil liberties and U.S. drone policy into the spotlight, what began as a one-man stand increasingly gained steam - and supporters - both in the Senate chamber and in social media throughout the day. 

Paul's traditional or "talking" filibuster -- dependent on one senator's control of the floor rather than a tally of votes -- continued into the wee hours as the Kentucky lawmaker pressed his case against the administration's policy on drone strikes on American soil.

It was the first use of the tactic since 2010, when Independent Sen. Bernie Sanders of Vermont held the Senate floor for eight hours and 37 minutes - a length Paul surpassed. 

The senator was joined on the floor throughout the day and night by other lawmakers, who stepped in to help continue the filibuster by asking lengthy questions on the Senate floor. His colleagues' contributions also included statements of support, the reading of tweets supporting Paul's efforts and the quoting of rap lyrics, Shakespearean prose and classic Hollywood films.

In a sign that Paul's cause had moved beyond just the most conservative wing of the party, Senate Minority Leader Mitch McConnell - Paul's fellow Kentuckian who is facing re-election in 2014 - joined close to midnight to offer support for Paul's "tenacity and conviction" and to announce that he will oppose CIA nominee John Brennan's confirmation. 

Republican Sens. Mike Lee of Utah, Ted Cruz and John Cornyn of Texas, Jerry Moran of Kansas, Saxby Chambliss of Georgia, Pat Toomey of Pennsylvania, Marco Rubio of Florida, Jeff Flake of Arizona, Ron Johnson of Wisconsin, Tim Scott of South Carolina, John Thune of South Dakota and John Barrasso of Wyoming -- as well as Democrat Ron Wyden of Oregon -- also participated. 

The filibuster continued late into the night despite earlier Democratic attempts to defuse it. 

First, Paul rebuffed Majority Leader Harry Reid's attempts to move to a vote on the nomination, pushing the final vote at least until Thursday. 

Hours later, Democratic Whip Dick Durbin of Illinois objected to Paul's request that the Senate take up a non-binding sense of the Senate resolution stating that the U.S. government cannot target "noncombatants" with drones on American soil. 

Arguing that such a resolution would be premature, Durbin instead invited Paul to testify at an upcoming hearing on the issue of drones. 

But that offer was not enough for Paul to halt his protest. 

Paul objects to what he calls the Obama administration's lack of clarity over whether a suspected terrorist who is an American citizen can be targeted with a drone strike within U.S. borders. 

In a response to a letter of inquiry, Attorney General Eric Holder wrote to Paul this week that such a targeted strike is "possible, I suppose" in a catastrophic circumstance, although the administration has "no intention" of doing so.

Paul began his filibuster as Holder testified before the Senate Judiciary Committee, where the attorney general reiterated some of that defense of the administration's policy. 

Hours into his filibuster, Paul acknowledged that Brennan is still likely to be confirmed, saying the lengthy delay is merely a "blip" in his nomination. But he and other participants emphasized that the debate is intended to shine a spotlight on the government's balance of civil liberties with national security. 

Over six hours after beginning the filibuster, a visibly tired Paul could be seen eating what appeared to be several pieces of candy in between sentences. At one point, Sen. Mark Kirk, R-Ill., set a thermos and an apple on his desk. 

"You must surely be making Jimmy Stewart smile," Cruz said of Paul upon taking the floor, alluding to the famous filibuster portrayed by the actor in the 1939 film "Mr. Smith Goes to Washington."

NBC's Mike Viqueira and Frank Thorp contributed to this report. 

This story was originally published on Wed Mar 6, 2013 12:34 PM EST

Saul Loeb / AFP - Getty Images

CIA director nominee John Brennan during a meeting on Capitol Hill in Washington on Jan. 31, 2013.

Amid new developments and revelations, President Barack Obama’s national security policies, past and future, are set to come under Senate scrutiny Thursday.

Most notably, Obama’s nominee to head the Central Intelligence Agency, John Brennan, will address what role the targeted killings of terrorists, either by using drone strikes or other means, have played and should play in national security policy.

Questions about targeted killings intensified Monday after a report by NBC News revealed a Justice Department memo which argued it was lawful for the president to target U.S. citizens who are leaders of al-Qaida or “an associated force.” Brennan will be appearing before the Senate Intelligence Committee for his confirmation hearing.

On Wednesday, an Obama administration official said the president had directed the Justice Department to give the congressional intelligence committees access to classified memos justifying the targeted killings policy. Until now the administration had refused to do this.  

Addressing the past on Thursday will be Defense Secretary Leon Panetta and Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, as they testify before the Armed Services Committee about the Sept. 11, 2012 attack on the U.S. diplomatic mission in Benghazi.

Senators on the panel -- especially Sen. Lindsey Graham, R-S.C. -- want to know how the U.S. military reacted to the attack, and what the Defense Department’s internal review revealed after the event.

The two hearings will feature contrasting political color: Republicans -- led by Graham, Sen. John McCain of Arizona and Sen. Kelly Ayotte of New Hampshire -- have been the ones who have made an issue of the Benghazi attack almost since it took place. They’ve implied that a full accounting of what happened was delayed until after the presidential election. Graham held up Obama’s nomination of Chuck Hagel to be defense secretary until he could get a chance to question Panetta about Benghazi.

But Obama’s drone policy -- directed largely by Brennan in his role as Obama’s counter-terrorism adviser -- has drawn criticism both from progressives on the left and those on the right who are fearful of an excessive concentration of power in the presidency.

On Benghazi, much is already known. In its report on the attack, the Senate Homeland Security and Governmental Affairs Committee said last December that Panetta’s Defense Department and Hillary Clinton’s State Department hadn't jointly studied the availability of U.S. military forces to defend or rescue the U.S. diplomats in Benghazi in the event of a crisis.

The Pentagon’s Africa Command didn’t have planes, helicopters, or other forces close to Benghazi on the day of the attack. “The Djibouti base was several thousand miles away. There was no Marine expeditionary unit, carrier group or a smaller group of U.S. ships closely located in the Mediterranean Sea that could have provided aerial or ground support or helped evacuate personnel from Benghazi,” the report said.

As for Brennan and drones, Micah Zenko, a fellow at the Council on Foreign Relations and author of a new report called “Reforming U.S. Drone Strike Policies,” said Obama’s choice of him as CIA director “now places him as the lead executive authority over all CIA drone strikes. The real question is whether John Brennan’s move from the White House to Langley to be director of the CIA is in fact an effort for the CIA to get out of the drone strikes business.”

Zenko noted that Panetta recently said that the Pentagon, not the CIA, should be conducting the drone strikes against al-Qaida suspects.

But Zenko cautioned against those who would head into the Brennan hearing with high hopes for new information. Having read transcripts of the past 10 CIA director confirmation hearings, he said, “It would be unprecedented if there were an in-depth discussion about ongoing covert activities.” The Senate Intelligence Committee “simply doesn't work that way, especially under chairman Sen. (Dianne) Feinstein” of California, he said.

Zenko added that the most useful line of questioning of Brenna would be regarding his conceptions of airpower. Brennan has repeatedly used the cancer analogy for air strikes killing terrorists without damaging the surrounding “tissue.”

“That's a dangerous, antiseptic, and unrealistic conception of military force,” Zenko said.

Interrogation vs. deadly strikes
But Obama spokesman Jay Carney told reporters at a White House briefing Wednesday, “Far fewer civilians lose their lives in an effort to go after senior leadership in al-Qaida” by using drone attacks “as opposed to an effort to invade a country with hundreds and thousands of troops and take cities and towns.” Implication: if you want to avoid another Iraq or Afghanistan, then support Obama’s drone policy.

Carney said Obama believes “that we need to move forward with more transparency as well as create, in his words, a legal framework around how these decisions are made.” But Obama believes he has the full constitutional authority to order targeted killings -- “transparency” or no transparency.

For those skeptical of Obama’s policy, there will be two other possible lines of questioning directed at Brennan:

1. Do the foreign policy costs of Obama’s use of drones -- alienating and angering people in Muslim countries -- outweigh its benefits?
2. Does the drone policy suggest that Obama would rather kill jihadists than capture them? Adding more detainees to those already held at Guantanamo -- a facility he pledged to close but hasn’t -- could amount to a political public relations headache.

The drone strikes have been unpopular in Pakistan and other countries. Making the case that drone strikes have high costs as well as benefits, the former U.S. commander in Afghanistan, Gen. Stanley McChrystal, told Reuters recently, “What scares me about drone strikes is how they are perceived around the world. The resentment created by American use of unmanned strikes … is much greater than the average American appreciates.”

Brennan has an opportunity on Thursday to rebut this view. He argued last August that “contrary to conventional wisdom, we see little evidence that these actions (drone strikes) are generating widespread anti-American sentiment or recruits” for al-Qaida. The targeted strikes against terrorists, he said, “are not the problem, they are part of the solution.”

Finally, Thursday’s Brennan hearing is a chance for senators on the panel to ask him whether Obama is using drone strikes as a less politically troublesome option than capturing detainees and putting them in Guantanamo.

This is an argument that former Bush administration officials such as ex-CIA director Gen. Michael Hayden and former CIA legal counsel John Rizzo have made.

Last week in a panel discussion at the American Enterprise Institute, a conservative Washington think tank, Hayden said interrogating al-Qaida operatives is a vital source of insight into the terrorists’ plans and capabilities:

But he warned, “We have made it so legally difficult and so politically dangerous to capture that it seems, from the outside looking in, that the default option is to take the terrorists off the battlefield in another sort of way” – in other words, by killing them. This could result in a loss of valuable intelligence.

Rizzo said, “It’s always been in the agency’s institutional DNA to want to collect intelligence by all sorts of means, especially human intelligence. You can’t collect human intelligence from a dead guy.”

Related:

White House: Congress to get classified drone info

4 key questions about controversial Justice Department drone memo

Legal experts fear implications of White House drone memo

Jewel Samad / AFP - Getty Images, file

White House counterterrorism adviser John Brennan's career includes a stint as CIA station chief in Saudi Arabia.

WASHINGTON -- Counterterrorism adviser John Brennan will be nominated as director of the Central Intelligence Agency by President Barack Obama, White House officials told NBC News on Monday.

Brennan worked at the CIA for 25 years, including a stint as station chief in Saudi Arabia. He also served as chief of staff to then CIA Director George Tenet from 1999 to 2001, when he was named the agency's deputy executive director. 

Obama was expected to make the announcement on Monday.

Full coverage from NBC Politics

As Brennan has been involved in major national security issues since 9/11, he should be able "to hit the ground running" at the CIA, one official told NBC News.

If confirmed, Brennan will succeed retired general David Petraeus, who resigned amid a scandal over an extramarital affair with his biographer.

On Sunday, an official told NBC News that Obama planned to nominate former Sen. Chuck Hagel to be secretary of defense.

Hagel is a moderate Republican and decorated Vietnam combat veteran who is likely to support a more rapid withdrawal of U.S. troops from Afghanistan. If confirmed, Hagel would give Obama a whiff of bipartisanship in his Cabinet. 

Senators signal tough fight for Hagel

The Hagel announcement was also scheduled for Monday.

Obama nominated Sen. John Kerry, D-Mass., as his next secretary of state in December, his first step in filling out his second term Cabinet and national security team.

NBC News' Peter Alexander and Reuters contributed to this report.

With the congressional storm over debt and spending temporarily calmed after the fiscal cliff fight, the political world's attention now turns to the administration's shuffling of top agency jobs at the start of President Barack Obama's second term.

The president's cabinet includes 15 heads of federal departments, appointed by the president and confirmed by the Senate. As Obama’s first term comes to an end, there remains plenty of uncertainty about as to the status of much of the cabinet, including some of the top positions in the government.  Here’s what we know so far: 

Secretary of State: Obama has already announced Sen. John Kerry as his pick to succeed departing Secretary of State Hillary Clinton, choosing the Foreign Relations Committee head after his other reported top choice, Susan Rice, withdrew from consideration for the post. Kerry is expected to be confirmed easily by his Senate colleagues.

Kevin Lamarque / Reuters

President Barack Obama announces the nomination of Sen. John Kerry as Secretary of State to succeed Hillary Clinton, at the White House in Washington Dec. 21, 2012.

Secretary of Defense: An administration official has confirmed to NBC's Chuck Todd that President Obama plans to nominate former Sen. Chuck Hagel, a Nebraska Republican and Vietnam veteran, for the Defense secretary position on Monday. Hagel would replace Leon Panetta at the helm of Defense Department.

The Nebraska lawmaker faces significant opposition from some in his own party who are wary of Hagel's past statements about Israel. Hagel was also forced to issue an apology after foes resurfaced a 1998 comment in which Hagel criticized an "aggressively gay" political appointee.

In an interview with NBC’s “Meet the Press” last week, Obama praised Hagel but said he has not made a final decision about who he wants for the top Pentagon job. 

"I haven't made a decision about who to nominate," Obama said. "And my number one criteria will be who's going to do the best job in helping to secure America."

If nominated, Hagel would be boosted by two heavyweights other than the president: Vice President Joe Biden and Rhode Island Sen. Jack Reed. 

Other possibilities reportedly discussed for the post were Former Undersecretary of Defense for Policy Michele Flournoy, or Deputy Defense Secretary Ashton Carter.

Treasury Secretary: Current Treasury Secretary Tim Geithner, the final remaining member of Obama's original economic team, has signaled that he will step down after the inauguration, which could leave the department without a confirmed chief during the coming showdown over the debt ceiling. White House Chief of Staff Jack Lew, a former director of the Office of Management and Budget, is considered to be Geithner's likely successor.

But as NBC's Political Unit notes, the White House may think twice about handling a confirmation process at the same time as yet another round of brinkmanship over the government's legal borrowing power.

Jason Reed / Reuters

President Barack Obama walks off stage with Treasury Secretary Tim Geithner after speaking about his meeting on infrastructure investment, in the Rose Garden of the White House in this Oct. 11, 2010 file photo.

CIA Director: While not technically a Cabinet position, also in the mix will be a new intelligence guru to replace former CIA Director Gen. David Petraeus, who resigned after admitting to an extramarital affair with his biographer.

In the running for that job are John Brennan, an influential White House adviser on counter-terrorism, as well as acting CIA Director Michael Morrell.

Other Cabinet positions:  Along with the candidates for those high-ranking positions, there will likely be other openings throughout the administration, with possible departures from other agencies including the Energy and Commerce departments.

If Interior Department head Ken Salazar chooses to leave, former Sen. Byron Dorgan of North Dakota, retiring Rep. Norm Dicks of Washington, and outgoing Washington Gov. Christine Gregoire are on the shortlist to replace him,  according to a Democratic insider.

Environmental Protection Agency head Lisa Jackson has also announced her departure at the end of January, setting up an open position at an organization frequently targeted by Republican foes of federal regulations. (The EPA chief job is not among the 15 official Cabinet positions but is awarded the status of "cabinet rank.")

House Intelligence Committee Chairman Mike Rogers, R-Mich., did little to tamp down speculation that he's under consideration to become the next CIA director, saying he could neither confirm nor deny conversations with the Obama administration about the vacant position. 

Speaking Tuesday on WJR radio in Detroit, Rogers, a former FBI agent who's helmed the intelligence panel for the past two years, acknowledged that his name has been among those in public discussion to replace David Petraeus as leader of the CIA. But he said he hd "every expectation" he would continue to serve as Intelligence Committee chairman.

A New York Times report following Petraeus's resignation in an adultery scandal named Rogers — along with deputy CIA Director Michael Morrell, Obama counterterrorism adviser John O. Brennan and former National Counterterrorism Center Director Michael Leiter — as potential picks to helm the CIA.

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Obama has shown a willingness during his first term to name Republicans to top security roles. For instance, he continued to involve Petraeus — a GOP favorite whose tenure begun under President George W. Bush — in security efforts, and kept Robert Gates as his defense secretary until mid-2011. 

What follows is a lightly edited transcript of relevant portions of Rogers's conversation Tuesday with WJR host Paul W. Smith:

Paul W. Smith: If you don't want the job, you can say so here and now, but it seems like you'd be a perfect fit for that kind of position, with your background.

Rep. Mike Rogers (R): Certainly, that name has been bandied about. They're going through a process now for that position. I have every expectation I will be the chairman of the House Intelligence Committee, which is a great job, it's where I want to be, and it's the kind of worth that I think is important for the country. 

[…]

Smith: Have you had any conversation that you can share with us, without getting into the details, regarding the position of director of the CIA with people who could be involved in that kind of decision-making process?

Rogers: I would not be able to confirm nor deny any discussions on the process they may be going through on the CIA director. I can tell you I have every expectation that I will be the chairman of the House Intelligence Committee in January.

[…]

Smith: Anything else, Mr. Director — I mean, congressman — that we need to talk about?

Rogers (laughing): It's going to be chairman of the House Intelligence Committee, a role that I'm honored and proud to serve in. And there's just a ton of work we're going to have to do in the next year. 

Smith: That doesn't mean you wouldn't accept the position, should it be offered.

Rogers: A) I doubt that's likely to happen, and B) I think it's important to have somebody that can walk in the office and sit down and have a level of trust.