The scheduled hearing was switched from 10 a.m. to 4 p.m. because of a joint meeting of Congress with South Korean President Park Geun-hye.
Senate Health, Education, Labor and Pensions Committee Chairman Tom HarkinTom HarkinGrassley challenger no stranger to defying odds Clinton ally stands between Sanders and chairmanship dream Do candidates care about our health or just how much it costs? MORE (D-Iowa) blasted the GOP on the floor arguing that Perez has been as "open and above board as he could possibly be throughout this entire confirmation process."
"I take great issue with the minority leader's suggestion today that Mr. Perez doesn't follow the law and believe that it applies to him," Harkin said.
"I would respectfully suggest that the Republican leader check his facts. To the contrary, Tom Perez has had a remarkable career as a result of a determination to make the promise of our civil rights statutes a reality for everyday Americans."
Earlier in the day, Senate Republican Leader Mitch McConnellMitch McConnellPath to 60 narrows for Trump pick Dems delay Senate panel vote on Supreme Court nominee This week: GOP picks up the pieces after healthcare defeat MORE (Ky.) said of Perez on the Senate floor that "all too often, he circumvents or ignores a law with which he disagrees."
But Harkin, who scheduled another vote for May 16, stood up for Perez and said he hoped that Republicans would eventually give Perez and up-or-down roll call on the Senate floor.
"There's absolutely nothing that calls into question his ability to fairly enforce the law as it is written and absolutely nothing that calls into question his professional integrity or his moral character or his ability to lead the Department of Labor," Harkin said.
Senate Budget Chairman Patty MurrayPatty MurrayInspector general reviewing HHS decision to halt ObamaCare ads Dems mock House GOP over lack of women in healthcare meeting The Hill’s Whip List: Where Dems stand on Trump’s Supreme Court nominee MORE (D-Wash.) chimed in on the clash and called out Senate Republicans for "once again playing politics with important, Cabinet-level nominations."
“Today’s political maneuver by Senate Republicans to block Mr. Perez’s confirmation process only serves to score political points while depriving the Department of Labor of a proven leader who is prepared to support our economy and workers across America," she said.
Harkin said Perez has done all that has been asked of him, including meeting with all lawmakers who requested a face-to-face, he has answered more than 200 written questions and he has "bent over backward to respond to any and all concerns about his work at the Department of Justice."
He argued that the Obama administration has produced thousands and documents and arranged for interviews with government employees and "have facilitated almost unprecedented levels of disclosure to alleviate any concern."
Harkin argued that he has had to postpone the vote on Perez for two weeks to provide more time for lawmakers to dig into his background but "all this process has revealed is that Mr. Perez acted at all times ethically and appropriately to advance the interests of the United States government."
"I'm incredibly proud of the work he's done at the Department of Justice to make those rights a reality after years of neglect," he said.
"He should be applauded, not vilified for the service he has provided to this country."
House and Senate Republicans contend that Perez acted unethically in a deal with city officials in St. Paul, Minn. They said he convinced the city to drop a Supreme Court appeal that would have had a potentially adverse effect on discrimination cases in exchange for the Justice Department's agreement to step away from two whistle-blower cases and forfeit upward of $200 million in damages for the federal government.
Democrats on both sides of the Capitol continue to argue that there is plenty of evidence to show that Perez followed all protocols in his cases at Justice, including St. Paul.
"In short, Mr. Perez did his job at DOJ and he did it well," which Harkin theorized was much of the source of the controversy generated around his nomination.
Meanwhile, the top Democrat and Republican on the House Oversight and Government Reform Committee sent a letter to Perez on Wednesday asking him to produce 1,200 emails in answer to a subpoena issued on April 10.
Panel Chairman Darrell Issa (R-Calif.) and ranking members Elijah Cummings (D-Md.) said the emails pertain to his use of a personal email account he allegedly used for Justice business.
A Senate aide told The Hill that about 97 percent of those emails have been gone through and there are only about 35 considered relevant.
“Senate Democrats should do more than just rubber-stamp questionable assertions made by the Justice Department," Ali Ahmad, communications adviser with the House Oversight and Government Reform Committee told The Hill in an email.
"DOJ lost credibility when it first tried to dismiss suggestions about possible violations of the Federal Records Act by Mr. Perez and then subsequently acknowledged violations once they knew investigators had proof. Until Mr. Perez provides all subpoenaed e-mails — and he has provided none to this point — the committee will not back down from its stance.”
This story was updated at 7:55 p.m.