House Oversight and Government Reform Committee Chairman Darrell Issa (R-Calif.) faces off with ranking member Elijah Cummings (D-Md.) after former Internal Revenue Service official Lois Lerner once again refused to answer questions at a congressional hearing. (The Washington Post)

The war between Democrats and Rep. Darrell Issa (R-Calif.), the controversial chairman of the House Oversight and Government Reform Committee, took on a new intensity Thursday when some Democratic lawmakers called for Issa to be stripped of his committee chairmanship.

“Mr. Issa is a disgrace and should not be allowed to continue in a leadership role,” Rep. Marcia L. Fudge (D-Ohio), who leads the Congressional Black Caucus, wrote in a strongly worded letter to House Speaker John A. Boehner (R-Ohio).

The uproar followed the latest clash between Issa and the committee’s top Democrat, Rep. Elijah E. Cummings (Md.), on Wednesday, when Issa abruptly ended a committee hearing without allowing Democrats to speak and cut off Cummings’s microphone while he was speaking.

In the letter to Boehner, Democrats described the behavior as “outrageous” and “disrespectful.”

But on Thursday, the House Republican leadership stood by Issa.

“Darrell Issa is the chairman, he’s done an effective job as chairman, and I support him,” Boehner told reporters during his weekly media address.

The clash came Wednesday morning as the committee met for a hearing as part of the investigation into the Internal Revenue Service’s targeting controversy. After peppering former IRS official Lois Lerner, who invoked her Fifth Amendment right against self-incrimination, with questions, Issa adjourned the meeting without giving Democrats an opportunity to speak.

Cummings asked that the hearing be continued, but Issa refused and had Cummings’s microphone turned off. Republicans on the panel, led by Issa, then walked out of the room while the enraged Maryland congressman continued to speak.

House Democrats also introduced a resolution Thursday reprimanding Issa, but the chamber voted along party lines to table it.

Cummings told reporters Thursday that several Republican members of the committee have since apologized to him for Issa’s conduct.

Later Thursday, Issa told U-T San Diego that he had reached out to Cummings and apologized.

“I could have offered to reopen the hearing and allowed him to make a second statement,” Issa told the newspaper. “As chairman, I should have been much more sensitive to the mood of what was going on, and I take responsibility.”

Cummings responded to the apology in a statement, saying: “My sincere hope is that as we move forward, we will respect the opinions of all members of the committee.”

In a press briefing earlier in the day, Cummings had said: “Chairman Issa wanted to hold a hearing, and then shut it down before the Democrats could utter one syllable. It is un-American.”

Friction between Issa and Cummings, neither of whom has established a reputation for diplomacy, stands in contrast to other committee leaders who have found ways to collaborate on controversial issues.

Republicans and Democrats both expressed outrage over the IRS’s targeting efforts after the actions became known last May, but the flare-up Wednesday serves as the latest sign of the partisanship and dysfunction that have dominated the oversight committee in recent years.

The IRS hearings appeared to be unfolding in a fashion similar to 2011, when the House voted to hold Attorney General Eric H. Holder Jr. in contempt of Congress for refusing to share information regarding a Justice Department gun-tracking program known as “Fast and Furious.”

In that case, Holder and Justice officials declined to grant several requests for information from Issa’s committee, citing executive privilege. After months of disputes — including several heated exchanges between Holder and GOP members of the committee — the panel voted to hold Holder in contempt, against strong objections from Democrats. Days later, a House vote made Holder the first sitting attorney general to be held in contempt of Congress.

The issue became a cause among conservative voters ahead of the 2012 presidential election, and both parties attempted to exploit the episode for political gain.

Now, House Democrats allege, Republicans are attempting to revive the IRS scandal as a political football and put it back in play for the upcoming midterm elections.

“What happened was so outrageous, so demeaning, so unjudicial, so awful in every respect,” said Rep. Louise M. Slaughter (N.Y.), senior Democrat on the House Rules Committee, who added that “we just absolutely have reached a boiling point.”

As Issa has pressed forward with the IRS investigation — periodically leaking snippets of evidence to support his theory that the IRS actions were attempts by the Obama administration to silence conservative critics — Cummings has cited information and findings to the contrary, declaring in a June interview with CNN that “the case is solved, and if it were me, I would wrap this case up and move on.”

Conservatives have griped that the clash between Issa and Cummings has overshadowed the hearing itself — during which Lerner did not answer questions about the investigation into whether the IRS targeted political groups for disproportionate scrutiny. On Thursday, Cummings hit back. He said that, had he been allowed to speak, he would have asked about the potential to have Lerner’s attorney address the committee, which he said could have helped provide answers to Issa’s questions.

On Thursday, several House Democrats alleged that, instead of truly seeking answers, Issa and other Republicans are using the hearings as a way to keep voters talking about the IRS investigation as the midterm elections approach.

“The Republicans are determined to keep this issue of the IRS alive,” said Rep. Sander M. Levin (Mich.), the ranking Democrat on the House Ways and Means Committee. “What happened yesterday was the political strategy of the Republicans: going berserk.”

Those criticism were echoed by House Minority Leader Nancy Pelosi (D-Calif.), who told reporters at her weekly news briefing that Issa’s behavior toward Cummings was disrespectful. She also said she was surprised that Boehner is standing by the California congressman.

“I can’t see how Republicans wouldn’t be running . . . to disassociate themselves from such behavior,” she said. “You would think they would be heading to the hills.”

Ed O’Keefe contributed to this report.