WASHINGTON - House Republicans criticized the handling of a whistle-blower case by President Obama's labor secretary nominee during a joint subcommittee hearing Tuesday dominated by sniping between panel members.

The contentious hearing, which involved members of the House Oversight and Judiciary Committees, came just one day before the Senate is set to vote on whether to confirm Assistant Attorney General Thomas Perez, who heads the Justice Department's civil rights division.

Under Perez's leadership, Justice's civil rights attorneys agreed not to assist in a whistle-blower complaint against the City of St. Paul, Minn., in exchange for the municipality dropping its Supreme Court challenge against certain housing-discrimination guidelines, according to House oversight investigators who interviewed the cabinet pick.

Key House and Senate Republicans said in an April report that the Justice Department's failure to intervene in the Minnesota whistle-blower case resulted in a missed opportunity to recover as much as $200 million in taxpayer funds awarded through "false certifications."

GOP lawmakers have suggested that Perez made the deal for ideological reasons - to keep the Supreme Court from weighing in on the legality of housing discrimination protections.

Perez has denied personal involvement with the decision not to sue St. Paul, telling lawmakers during a Senate confirmation hearing in April that lower-level Justice Department attorneys made the decision.

Shelly Slade, a former Justice attorney who specialized in cases involving fraud against the government, testified during the hearing that she would have recommended declining the whistle-blower case, partly on grounds that it was not winnable.