Issa and Cummings

Committee chairman Rep. Darrell Issa (R-Calif.) (R) cuts ranking member Rep. Elijah Cummings (D-MD) off during a hearing of the House Oversight and Government Reform Committee on Capitol Hill March 5, 2014 in Washington, DC. Cummings was cut off after Issa only allowed his own questions of witness Lois Lerner, former director of the Tax Exempt and Government Entities Division at the Internal Revenue Service, during the hearing to see if the Internal Revenue Service has been targeting US citizens based on their political beliefs. (AFP/Getty Images / March 5, 2014)

A push by congressional Republicans on Friday to increase pressure on the Obama White House over the 2012 attack on the U.S. diplomatic mission in Benghazi, Libya, has put Baltimore Rep. Elijah E. Cummings back to his role as one of the administration's leading defenders.

Cummings, the top Democrat on the House Oversight Committee, was among the first to respond to the GOP's decision to subpoena Secretary of State John Kerry. He described the move as "shockingly disrespectful" and accused GOP leaders of being "in disarray."

"These actions are not a responsible approach to congressional oversight," Cummings said. "They continue a trend of generating unnecessary conflict for the sake of publicity."

Pushing back has become a familiar task for the 63-year-old lawmaker, now entering his fourth year leading Democrats on the contentious oversight panel. Sometimes reserved and sometimes holding forth at the top of his lungs, Cummings has carved out a national profile as one of his party's top fighters.

He has battled with the Republican chairman of the committee, Rep. Darrell Issa of California, over Obamacare, the federal gun-walking scandal known as Fast and Furious and, recently, the controversy over the IRS targeting of conservative groups.

His already famously rocky relationship with Issa deteriorated further this spring when the Republican suggested Cummings might have helped bring one of the tea party groups to the attention of the IRS office tasked with deciding which organizations qualify for tax-exempt status.

Cummings denied doing so — and the imbroglio appears to have strengthened support for him within the party. But it also has increasingly made him a target of conservative Republicans.

"I wonder sometimes, when I'm talking to Issa, if there will come a day when he'll look back on his life and say, 'We could have made a difference,' " Cummings said in an interview with The Baltimore Sun before Friday's maneuverings on Benghazi. "There are times where I mourn what could have been with regard to this committee — things we could have done."

The Committee on Oversight and Government Reform has a history of bare-knuckle politics that predates the leadership of Issa and Cummings, both of whom began in their roles in 2011. Former Rep. Dan Burton, an Indiana Republican, used his chairmanship to aggressively pursue President Bill Clinton, whom he once referred to as a "scumbag."

Rep. Henry A. Waxman, the committee's Democratic chairman in 2007 and 2008, investigated the administration of President George W. Bush on its handling of the Iraq War and response to Hurricane Katrina, as well as in connection with disgraced lobbyist Jack Abramoff.

Republicans have accused Cummings of being an obstructionist. They note that he was chosen for the top job over more senior committee members in part because he was seen as more assertive and, in his own words, willing to go "toe to toe on everything."

"Unfortunately, [he] has been true to his rhetoric about 'going toe to toe' to obstruct oversight on behalf of the White House," Issa spokesman Frederick Hill said in a statement. "His tenure as ranking member has further eroded the American people's confidence that this president's party is capable of conducting necessary and constitutionally mandated oversight."

The committee has held four hearings on the attack in Benghazi, a city in eastern Libya, on Sept. 11, 2012, nearly a year after the U.S.-backed ouster of Muammar Khadafi. Four Americans, including Ambassador J. Christopher Stevens, were killed.

Republicans have for years accused the White House of falsely blaming the attack on spontaneous protests against a crude anti-Islamic video produced in the United States.

It was revealed to have been an organized plot by dozens of gunmen believed to have been linked to al Qaida — but the GOP says the administration tried to suppress that conclusion because it contradicted President Barack Obama's assertion that the U.S. had the terror group "on the run" ahead of the 2012 presidential election.

The controversy expanded this week when a newly released email showed a White House aide had crafted talking points for Susan Rice, then the ambassador to the United Nations, in the days after the attack.

The White House has said Rice's comments were based on the intelligence available at the time.

Issa, expressing outrage that the State Department had not previously disclosed the email, said Friday its revelation represents a "disturbing disregard for the department's legal obligations to Congress." And he issued the subpoena, calling on Kerry to testify before the committee May 21.

Hours later, House Speaker John Boehner said he would create a select committee to investigate the issue — a decision that will draw still more attention to the controversy.

It's not yet clear whether Issa or Cummings will serve on the select committee.