In this April 18 photo, Labor Secretary nominee Thomas Perez testifies on Capitol Hill. A confirmation vote on his nomination has been delayed again. (Molly Riley/AP)

Senate Democrats on Wednesday accused Republicans of invoking an obscure procedural rule to postpone committee action on President Obama’s nominee for labor secretary.

Senate rules require the consent of both party leaders for committees to meet after the Senate has been in session more than two hours. That rule applied to a hearing of the Health, Education, Labor and Pensions Committee scheduled for 4 p.m. to consider a confirmation vote for Thomas ­Perez, who currently heads the Justice Department’s civil rights division.

Lawmakers disagreed Wednesday over who caused the delay, which was rescheduled for next Wednesday.

Sen. Tom Harkin (D-Iowa), who chairs the committee, accused Republicans of invoking the two-hour rule, but GOP lawmakers said that technically they never opposed the meeting.

Don Stewart, a spokesman for Senate Minority Leader Mitch McConnell (R-Ky.), said that Harkin rescheduled the session after simply learning that Republicans planned to invoke the rule.

Harkin took to the Senate floor to state his frustration.

“Republican obstructionism and procedural tricks are preventing this body from carrying out its duties, including its obligation to consider important presidential nominations,” Harkin said in his floor speech. “This continuing delay is unconscionable and only hurts the American workers and businesses that rely on the Department of Labor each and every day.”

Harkin noted that he had postponed the committee meeting two weeks ago to placate GOP lawmakers who wanted more time to examine Perez’s tenure at the civil rights division.

Critics have said that Perez agreed not to assist in a whistleblower complaint against the city of St. Paul, Minn., in exchange for the city dropping its Supreme Court challenge of housing-discrimination guidelines. Republicans have suggested that Perez made the deal to keep the justices from weighing in on the legality of the housing protections.

Perez told lawmakers at a previous hearing that he had not been involved in the decision not to sue St. Paul. But he acknowledged a role in St. Paul’s decision to drop its Supreme Court challenge, saying that it was in the best interest of the nation and that the move had been approved by senior Justice officials. Others have added that it’s not unusual for the broader interests of the government to be taken into account in such circumstances.

On Tuesday, House lawmakers clashed at a hearing to examine that deal, as well as issues surrounding Perez’s use of a personal e-mail account to handle official business.

Perez, an assistant U.S. attorney general, has faced more resistance than perhaps any of Obama’s second-term Cabinet picks except Defense Secretary Chuck Hagel, whose confirmation proceedings dragged on for nearly two months.

McConnell, in a speech Wednesday on the Senate floor, described Perez as a “committed ideologue.” “His willingness, time and again, to bend or ignore the law and to misstate the facts in order to advance his far-left ideology led me and others to conclude that he’d continue to do so if he were confirmed to another, and much more consequential, position of public trust,” he said.

Harkin said that Republicans had run out of excuses for postponing a confirmation vote. “This time, there is no allegation that they have had insufficient time for consideration — just delay for its own sake,” he said. “As our country continues to move down the road to economic recovery, the work of the Labor Department is becoming even more vital to the lives of working families.”