Drafters are racing to complete the text of a comprehensive immigration reform bill slated to be unveiled on Tuesday, with minor loose ends causing some in the Senate’s Gang of Eight to urge a delay to presenting the sweeping legislation.

But, with pressure growing after multiple missed deadlines for the completion of the reform bill, sources within the group tell NBC News that the proposal is still likely to be formally presented in a press conference tomorrow.

The Senate Judiciary Committee was expected to hold its first hearing on the legislation on Wednesday, but that has now been postponed to Friday. An additional hearing will be held next Monday as well. 

Senate Republicans and Democrats have yet to be briefed on the legislation in their respective formal meetings. The bill includes the opportunity -- if certain border security criteria have been met -- for qualified undocumented immigrants to obtain probationary legal status for 10 years before becoming eligible to apply for a visa.

Republicans are expected to meet tonight at 5:45 pm to review the plan within their own conference. (Lead GOP negotiator Sen. Marco Rubio of Florida was originally scheduled to brief his colleagues last week, but lengthy discussion of pending gun legislation pushed the presentation off the agenda.)At noon on Tuesday, Republicans also plan to sell the plan to outside conservative interest groups.

Democrats have yet not scheduled an internal briefing but would likely share the bill with colleagues during a regularly scheduled Tuesday lunch meeting tomorrow.  

UPDATED 2:27 PM ET:  House Speaker John Boehner Tuesday repeatedly challenged the president's willingness to go against his own party on issues that include reforms to social programs and spending.

"I think he'd like to deal with it [fiscal problems], but to do the kind of heavy lifting that needs to be done, I don't think he's got the guts to do it,” the Ohio Republican said in a meeting with a small group of reporters for nearly an hour Tuesday morning. “He understands there is a spending problem. He understands that we need changes and reforms, and we need to solve these problems."

When pressed about the severity of that statement, he modified, saying the president does not have the "courage."

Washington is in the midst of yet another fiscal crisis, facing a political showdown over so-called "sequestration," the self-imposed round of across-the-board spending cuts to domestic programs and the Pentagon. The sequester was supported by both the White House and Congress as a way to encourage lawmakers to find common ground. Instead, they have been mired in a stalemate, unable to find an equitable solution for both sides. 

"I am not suggesting that this is easy,” Boehner said, “but what I am suggesting is that he is the President of the United States. This is the biggest threat to our society."

J. Scott Applewhite / AP

House Speaker John Boehner, R-Ohio, repeats his call for President Obama to submit a budget proposal to Congress, during a news conference at the Capitol in Washington, Wednesday, Feb. 6, 2013.

President Obama campaigned on raising taxes on the wealthy and got that in the showdown over the fiscal cliff. He wants more revenue -- from what he says are "loopholes and deductions" for the wealthy. Republicans have balked at that notion, saying he already got all the revenue he was going to get.

The White House has accused Boehner of walking away from "grand bargains," deals to reduce the country's deficits, in both 2011 and 2012 because he could not sell it to his base. Boehner's office vehemently disagrees with that notion, instead pointing the finger back at the president.

Republicans also feel as if they have already given in and do not want to give more, particularly after passing the tax increase and punting on the debt ceiling, voting to suspend it temporarily until the Democratic-controlled Senate passes a budget, something it has not done in years.

But those maneuvers have not been without staunch GOP opposition and misfires. President Obama and Boehner were thought to be, once again, close to a deal when Boehner abruptly announced "Plan B," an initiative pushed by House leadership, including Majority Leader Eric Cantor (R-VA), that would have let tax cuts expire for millionaires. But Boehner pulled the measure after he realized it did not have majority support within his conference.

Instead, Boehner issued a statement urging President Obama and the Democratic-controlled Senate to pass something to avert the fiscal cliff. Boehner eventually brought the Senate-passed measure to the House floor. It passed without majority GOP support.

On immigration, Boehner claimed in the meeting, "The thing I am most concerned about immigration reform is the president getting in the way. Sometimes I think he'd rather have an issue than a solution. Here's the guy who four years ago said he was going to have immigration reform, and he's done absolutely nothing for four years. I hope the president will play a constructive role."

Democrats say that prior to the 2012 presidential election, they have faced a brick wall of opposition on immigration, despite President Obama's promises, especially from House Republicans. In December 2010, Senate Republicans filibustered the DREAM Act, which would have given a pathway to citizenship for children brought to the United States illegally. President Obama supported the measure, and it got 55 votes, five short of the required 60 to overcome a filibuster.

But since Obama's re-election, in which he won 71 percent of the Hispanic vote, Republicans have sounded a different tune on immigration.

Sen. Marco Rubio (R-FL), who will give the GOP response and is leading an immigration-reform effort in the Senate, dropped by the meeting as well.

"I didn't mean to interrupt--,” Rubio said, as he looked for a cup of coffee.

When asked if he is feeling any pressure tonight, he gave a big smile and said, "No."

UPDATED 11: 40 AM ET: There is an emerging deal to avert the fiscal cliff, led by negotiations between Senate Minority Leader Mitch McConnell and Vice President Joe Biden, but the key sticking point remains the sequester and deficit reduction, aides say.

Biden and Republican Leader Mitch McConnell exchanged phone calls until about midnight last night and aides continued beyond that, aides tell NBC News. Democratic Leader Harry Reid left Capitol Hill in the evening Sunday and was not directly involved last night.

Aides say the Vice President and McConnell spoke at 12:45 am and again at 6:30 am this morning. GOP sources say the inclusion of the vice president has made a favorable difference in the talks, given his understanding of legislation and his personal relationships.
Two senior aides to McConnell continued with White House representatives overnight and again today.

GOP aides say they expect their party to likely defer its biggest fight over deficit reduction when the debt-ceiling debate takes center stage in the new year. Republicans say given the time left, there is limited, if no chance, to secure specific detailed alternative spending cuts right now.  

Republicans would like to see the "sequester" across the board cuts kept in place to drive down the deficit, but Democrats are resisting that and offer a two-year delay.

But Democrats caution that the "emerging deal" which "creates another cliff in three months probably would not have the votes to pass the two chambers." That is a reference to the looming fights over the debt ceiling and the overall government budget deadline in March.

Democrats also argue the new revenue generated by tax increases, especially if reduced from the Democrats' earlier targets, should be used to cover the costs of delaying the automatic spending cuts for two years and protecting the long-term jobless with extended benefits. 

Cuts that would go into effect as a result of the sequester would be deep and across the board. The discretionary cuts were signed into law in an effort law to compel Washington to address the long-term deficit. So far, the parties have been unable to agree on replacement cuts that would be targeted and therefore less arbitrary.

The most recent Democratic offer on taxes, presented on Saturday night, is setting the new income threshold at $450,000, sources say. That represents an increase over the president's original $250,000 threshold for higher rates and Obama's later offer to Boehner of $400,000.

Senior Republicans say the GOP is looking for a figure at about $550,000, down from House Speaker John Boehner's $1 million and retaining current estate tax rates. That could mean, say various members, a split-the-difference deal at $500,000.

Significant progress has been made on the income tax threshold and estates taxes, but the figures will not be set in stone until all details are resolved, including unemployment benefits, preventing a scheduled cut to medical provider's Medicare payments (know as the Doc Fix), and a fix to remove millions of middle class taxpayers from the "alternative minimum tax."

The taxes being discussed, by the way, would be made permanent and not given a "sunset provision" in law, which is unusual. There would be no expiration date like the one that forced this debate.

While Wisconsin Republican Paul Ryan's national public identity has been more fiscal hawk than culture warrior, Ryan has long been a strong opponent of abortion rights who believes that life begins at conception.

And he has pursued and supported legislation that backs up those socially conservative views.

The Todd Akin episode invited a closer look at Ryan's record on abortion and social issues. While Ryan has flatly rejected Akin's reference to "legitimate rape," Ryan's name and his vote are tied to instances in which the term "forcible rape" appeared in legislation. The bills sought to place limits on access to abortion or health insurance coverage for an abortion.

Three years ago, the then-39-year-old congressman co-sponsored an abortion-related amendment called "Limitations on Abortion Mandates."

That proposed amendment was blocked in what was a Democratic-controlled House Ways and Means Committee. Ryan and only one co-sponsor, Rep. Sam Johnson of Texas, proposed a change to health-care legislation that would have required health insurance cover abortion services. 

The Ryan-Johnson failed amendment did specify limited exceptions, permitting abortion coverage including when the life of the mother is at stake and in line 16 of the proposed text "... unless the pregnancy is the result of an act of forcible rape or incest."

More recently and more widely covered, Ryan was among a much larger group of 186 co-sponsors that included Akin of H.R. 5939, "To prohibit taxpayer funded abortions and to provide for conscience protections...." 

Again, the text of the 2010 bill, typically written by committee senior staff, included nearly the same wording as his July 2009 amendment with the term "forcible rape." The language in lines 15 and 16 reads: "(1) if the pregnancy is the result of an act of forcible rape, or incest with a minor...."

Aides to the Romney-Ryan campaign say the congressman has been "clear and consistent that rape is rape." Ryan did not defend the term "forcible," saying this week, "There is no splitting hairs over rape."

Asked why Ryan backed measures that referred to "forcible rape," advisers say Ryan has supported other abortion-related bills that have not contained that language.

For broader context, the term "forcible rape" appears to have roots in the legal community, where it has been used by prosecutors to distinguish that crime from "statutory rape," which involves a minor unable to legally consent or a person who lacks mental capacity for legal consent.

*** UPDATE *** The Romney-Ryan campaign points out that Ryan did not initiate the "Limitations on Abortion Mandates" amendment that included the term "forcible rape." That amendment failed to get out of committee in July, 2009 during the health care debate. The amendment was proposed by and carried the name of a more senior Republican colleague, Rep. Sam Johnson of Texas. Ryan joined Johnson in offering the amendment. Ryan was identified in the ea rlier post as a "co-sponsor" of the amendment, but that isn't technically the correct term.  

That said, Ryan did vote in support of the amendment with all other Republicans on the committee. Further, the measure also had the support of three Democrats, Reps. Pomeroy, Tanner and Pascrell. The amendment was defeated.

Even as many in the GOP called on Congressman Todd Akin to resign from the Missouri Senate race following his inflammatory comments on rape, Akin allies remained defiant.

NBC News has learned that the Missouri Republican is in Ohio today. He is doing radio interviews and "more filming" for TV ads.

Sources around Akin dismiss the calls for him to withdraw by 5 pm Central time saying, "The only deadline is November."

Advisers say that the six-term Missouri congressman remains "confident that he can beat Claire McCaskill, and he's prepared to do it."

Despite intense pressure from national elected officials and conservative voices to exit the race, "This isn't stressful for Todd," says a close associate. 

"This is a time for him to reach within, as he has, and stand up for what he has his entire life, what he believes in."

Advisers dismiss the critics as largely coming from Washington, adding that it's "easy to vilify someone you don't know" and claiming it's "not surprising for political figures to respond to the problem this way."   

Akin is ignoring the non-elected conservatives, who are upset with him as well. His advisers push back that those critics "might have the opportunity to reconsider" and "re-evaluate" as Akin continues his campaign.

Team Akin also asserts that those "putting out releases" were never his constituency. Their chief defense is that Akin has been "authentic and transparent" in his apology and that he is "openly hurting for anyone he hurt" with his comments. The newly released ad is described as an effort to give voters an opportunity to "see his heart in this circumstance."  

On the seemingly dire politics of staying in the race, Akin advisers assert, "The truth might work," referring to what they consider his sincere apology. 

Projecting unusual confidence in the face of so much opposition, advisers even predicted that Akin will be sworn into office in January "stronger having endured and overcome." 

And they claim he will consider this experience a "blessing," because Akin would have a new national audience for his grassroots causes and be better able to speak to people who believe the political process has "left them by the side of the road."

Speaker John Boehner told his Republican House members Tuesday night that "Paul Ryan gives us the ability to go on offense" in the battle over Medicare following Ryan's selection as Mitt Romney's running mate.

That message, described by senior aides, came during a regular recess conference call while members are home in their districts and campaigning for re-election.

J. Scott Applewhite / AP

House Speaker John Boehner talks about a lunch meeting with President Obama to deal with rising gasoline prices, at the Capitol in Washington, Feb. 29, 2012.

Boehner appeared to offer reassurance saying, "The pundits are buzzing that with Paul on the ticket, the Democrats are going to attack us on Medicare.  Well, here's a news flash -- they were gonna do that anyway."  

GOP leadership wants voters to hear their argument that Republicans are "the only ones" who have taken action to preserve Medicare in the budget they passed while the president's health care law they claim, "raided Medicare by $700 billion."

The speaker stressed that jobs and the economy must remain their top issues, but he also gave guidance on how House Republicans should frame other key arguments. On Romney's tax returns, Boehner pointed to Ryan's "60 Minutes" response: "The American people aren't asking where are the tax returns; they're asking, 'Where are the jobs?'" On stalled drought relief, Boehner pointed out that the president, in Iowa, criticized Ryan for congressional inaction. Boehner countered that the House did pass its version of help for farmers while the Senate did not tackle drought relief.

Boehner accused President Obama of being "desperate to shift the conversation away from his record on jobs and the economy." The speaker encouraged an aggressive stay on offense strategy saying, "If we keep that kind of focus and discipline, the American people will be with us."

Yet on the issue of Medicare, Democrats today fired back, with Sen. Chuck Schumer issuing this memo:

The case for Paul Ryan goes something like this: even if you disagree with his policy ideas, his proposals at least represent a good-faith appeal for deficit reduction that is both serious and statesmanlike.

This appears to be the message Mitt Romney hopes to sell with his risky selection of Ryan as his running mate. But it is an utter myth. In Ryan's budget, the savings achieved by his plan to privatize Medicare and gut investments in the middle class do not go towards reducing the deficit, but rather to pay for further tax cuts for the wealthy.