In a case that could affect Republicans’ standing with Latino voters, Sen. Charles Grassley, R- Iowa, is pledging to block Senate confirmation of President Barack Obama’s nominee for labor secretary, Thomas Perez.

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Ranking Member Senator Chuck Grassley, R-IA, questions Homeland Security Secretary Janet Napolitano as she testifies before the Senate Judiciary Committee on Capitol Hill, Feb. 13, 2013, on comprehensive immigration reform.

Grassley accuses Perez – now the assistant attorney general for civil rights – of improperly arranging a swap. If the city of St. Paul, Minn. would withdraw a major fair housing case which was about to be argued before the Supreme Court, then the Justice Department would agree to not go to court in support of a whistleblower suing the city.

Perez testified at his confirmation hearing Thursday before the Senate Health, Education, Labor and Pensions (HELP) Committee that he had acted properly in the St. Paul cases, and that the pivotal decision on the whistleblower was made not by him but by Assistant Attorney General Tony West and career Justice Department attorney Michael Hertz.

Perez said Hertz had decided that whistleblower Frederick Newell, who alleged misuse of federal funds by the city of St. Paul, had a weak case that didn’t merit intervention by the Justice Department on his side.

Grassley, the top Republican on the Senate Judiciary Committee, is taking a special interest in the Perez nomination because he was the chief sponsor of the 1986 version of the whistleblower law – the False Claims Act—which allows people who uncover fraud in government programs to receive a portion of recovered damages and to be protected from retaliation.

Grassley said Wednesday evening before Perez’s confirmation hearing, that he “is supposed to be representing the United States of America and he has all these people in the Justice Department that are professional people and they decide what False Claims cases you take – and he interfered with that.”

Grassley added, “We had the prospects of winning a $200 million False Claims case. We had a whistleblower that goes out on a limb to bring it to the government’s attention. There’s some case before the Supreme Court that he (Perez) doesn’t want them to rule on, so he gets the city to remove it (from the high court docket) – doesn’t that sound like it’s not in the public interest?”

Grassley said he would object to the Senate even taking up the Perez nomination for a vote.

Addressing Republicans’ vulnerability with Latino voters, Congressional Hispanic Caucus Chairman Rep. Rubén Hinojosa, D- Texas, said Tuesday, "For a party that is trying to overcome racially insensitive comments and engage the Hispanic community, I would suggest not smearing a highly qualified Latino cabinet nominee.”

But when asked whether the Perez battle might risk damaging the Republican Party’s appeal to Latinos, Grassley replied, “There are plenty of qualified Latino people that haven’t forgotten their public responsibilities.”

Perez won strong support from HELP Committee chairman Sen. Tom Harkin, D- Iowa, at Thursday’s hearing. “Frankly I’m surprised” that Republican senators are criticizing Perez for intervening in the St. Paul case, Harkin said. “Lawyers make strategic judgments all the time about what cases should be appealed, and given the stakes in this matter, and the importance of strong enforcement of the Fair Housing Act, I think it’s clear the department made the right call.”

Harkin added that he had examined the case with a “fine-tooth comb” and told Perez “the evidence clearly shows that you acted ethically and appropriately at all times.”

Perez told Harkin that it was city officials, not him, who first suggested the idea of linking the decision to withdraw the civil rights case in which the city was a party and the decision by the Justice Department to not side with whistleblower Newell.

Perhaps more important than the whistleblower aspect of the case is the effort by Perez to avoid an potentially unfavorable Supreme Court ruling on the use of a legal theory called “disparate impact” in cases under the Fair Housing Act.

Under disparate impact analysis, a plaintiff need not prove that the defendant intended to discriminate on the basis of race. Instead, disparate impact looks at whether the defendant had a policy that resulted in a statistical disparity in the way members of a racial or ethnic minority were treated.

After discussions with Perez early in 2012, the city of Saint Paul agreed to withdraw a fair housing case which was only three weeks away from its oral argument in the Supreme Court.

The case, Magner v. Gallagher, arose out of attempts by the city of St. Paul to aggressively enforce housing code violations against apartment owners who rented to low-income tenants.

In response, a group of St. Paul landlords made the argument that a disproportionate number of their renters were African-American and that the city’s aggressive enforcement of the housing code would have the effect of increasing costs, raising rents, and shrinking the number of rental units for African-American tenants. Thus the city’s policy would have a “disparate impact” on a racial minority, they contended.

But if the justices had rejected this argument and disallowed the use of disparate impact in fair housing cases, it could have had ripple effects on other civil rights laws.

At Thursday’s hearing, Perez told Sen. Lamar Alexander, R- Tenn., the ranking Republican on the HELP committee, “Bad facts make bad law and I thought that this (Magner v. Gallagher) case was a poor vehicle” for raising the issue of the use of disparate impact in enforcing the Fair Housing Act.

Alexander accused Perez of “an extraordinary amount of wheeling and dealing outside the normal responsibilities of the assistant attorney general for civil rights….It seems to me you’re manipulating the legal process to try to get the result you want from the Supreme Court in a way that that’s inappropriate….”

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U.S. Supreme Court members (first row L-R) Associate Justice Clarence Thomas, Associate Justice Antonin Scalia, Chief Justice John Roberts, Associate Justice Anthony Kennedy, Associate Justice Ruth Bader Ginsburg, (back row L-R) Associate Justice Sonia Sotomayor, Associate Justice Stephen Breyer, Associate Justice Samuel Alito and Associate Justice Elena Kagan.

The U.S. Supreme Court this week will consider whether a landmark civil rights law, the Voting Rights Act, remains constitutionally valid, given the growth in the political power of minority voters and candidates.

Civil rights groups fear the court's conservatives are prepared to gut what the ACLU calls "the most important piece of civil rights legislation Congress has ever enacted."

The justices will hear oral arguments in the case Wednesday and rule sometime before the current court term ends in late June.

Passed by Congress in 1965 and renewed four times since then, most recently in 2006, a key provision of the law requires states with a history of discrimination at the polls to get federal permission before making any changes to their election procedures — from congressional redistricting to changing the locations of polling places.

The law was at the core of last year's successful efforts to block strict voter photo ID laws in Texas and South Carolina and to prevent Texas from redrawing its legislative and congressional boundaries in a manner that challengers claimed would have discriminated against minority voters.

"The last election vividly showed that voter suppression and voting discrimination are not just problems of the past. They continue to undermine our democratic process," says the ACLU's Steve Shapiro.

The challenge to the law comes from Shelby County, Alabama, a mostly white suburb south of Birmingham.  It argues that the pre-clearance requirement — which covers nine entire states and 66 counties or townships in seven others — is unconstitutional.

The areas covered by the law, it says, include some localities that have made substantial reforms but leave out other parts of the country that have failed to root out discrimination at the polls.

"Florida has been forced into pre-clearance litigation to prove that reducing early voting from 14 days to 8 is not discriminatory, when states such as Connecticut, Rhode Island, and Pennsylvania have no early voting at all," says Bert Rein of Washington, DC, the lawyer for the county.

While the history of blatant discrimination at the polls justified renewing the law in the past, Shelby County says, Congress failed to marshal enough evidence in 2006 to justify extending it for another 25 years.  "At most, the 2006 legislative record shows scattered and limited interference with voting rights, a level plainly insufficient" to sustain the pre-clearance requirement, Rein says.

Since 1990, adds Alabama’s Attorney General, Luther Strange, African Americans in the state have registered and voted in larger percentages than in states outside the South.

“African Americans hold seats in the legislature at percentages that are roughly commensurate with Alabama’s 26 percent African-American population,” Strange says.

But the NAACP Legal Defense and Education Fund says the current map is a close enough fit to cover the areas of greatest concern.  "Congress is not a surgeon with a scalpel when it acts to legislate across the fivty states, but it can reasonably attack discrimination where it finds it," the group says.

If the law were struck down, civil rights groups fear the areas covered by the law would revert to their old habits.

Warns the Leadership Conference on Civil and Human rights, “There is a significant risk of backsliding and a likelihood that millions of minority voters will face new barriers to the exercise of their most fundamental human right.”

President Obama expressed a similar sentiment in a radio interview last week. If covered jurisdictions no longer had to defend their electoral changes in advance, Obama said, civil rights groups would be forced to file lawsuits after voting changes were already in place.

“There are some parts of the country where obviously folks have been trying to make it harder for people to vote. So generally speaking, you’d see less protection before an election with respect to voting rights,” Mr. Obama said.

The Justice Department, which is defending the law before the Supreme Court, argues that the coverage formula is flexible, allowing local governments to bail out of the pre-clearance requirement if they can demonstrate they have not discriminated against minority voters for at least ten years.

During the past three decades, 38 bailouts have been granted, freeing 196 local jurisdictions of the preclearance requirement, the Justice Department says.  They include the first ever granted from parts of Alabama, Georgia, Texas, and Virginia, four of the states that are otherwise covered by the law.

Four years ago, the Supreme Court strongly suggested that several justices had doubts about its constitutionality, given recent electoral reforms. "Things have changed in the South," the court said in 2009.  "Blatantly discriminatory evasions of federal decrees are rare."

The court then went on to reject a constitutional challenge to the pre-clearance requirement, but it strongly suggested Congress should update the coverage formula.  Because, however, no changes have since made, the court may prepared to go the rest of the way this time.