Rep. Darrell Issa (R-Calif.) and Attorney General Eric Holder sparred during the House Judiciary Committee’s hearing on Wednesday. Holder called Issa’s conduct “shameful” and “unacceptable.” (The Washington Post)

After two years of feverishly chasing any hint or suggestion of wrongdoing by the Obama administration, Rep. Darrell Issa (R-Calif.) may finally be having his moment.

Issa, the chief congressional watchdog over the White House, has the administration squarely on the defensive on two of the most politically explosive events of the moment: last year’s deadly attack on the U.S. compound in Benghazi, Libya, and the Internal Revenue Service’s targeting of conservative groups seeking tax-exempt status in the run-up to the 2012 elections.

Issa’s double-barreled investigations have forced the administration to navigate some of Washington’s most cliched political territory — explaining what officials knew, and when they knew it.

The scandals have overshadowed Obama’s legislative agenda for the past two weeks, even turning a news conference with British Prime Minister David Cameron meant to focus on the Syrian civil war into a sideshow about GOP investigations.

How much long-term damage these probes do to Obama’s second-term efforts will depend on what Issa and his team of investigators uncover. The controversies also have bestowed, finally, on Issa and the Oversight and Government Reform Committee the kind of prominent investigative role that Issa had promised to play when he claimed the chairman’s gavel in January 2011.

“Now he’s got a couple things coming up that will prove his mettle,” said former congressman Tom Davis of Virginia, a onetime top Republican on the panel who still advises Issa. “He’s got a couple of aces, as long as he doesn’t overplay his hand.”

But the White House is banking on Issa overplaying his hand; Democrats say that is his preternatural instinct and a tendency that has undermined his credibility in the past.

The mutual antipathy came to a head Wednesday afternoon when Attorney General Eric H. Holder Jr. appeared before the Judiciary Committee, on which Issa is a senior member, not chairman. The two clashed in a heated 10-minute exchange that began over several policy matters but devolved into a bickering match in which Issa demanded that Holder adhere to committee rules and answer his questions.

“I’m not going to stop talking now. You have characterized something,” Holder interjected as the two talked over each other. “It is too consistent with the way in which you conduct yourself as a member of Congress. It’s unacceptable, and it’s shameful.”

After the 2010 midterm elections vaulted Republicans into the majority, Issa’s chairmanship of the oversight committee became one of the leading legislative symbols of the tea party revolution, carrying with it the hope of exposing any possible wrong­doing in the West Wing.

Two weeks before Election Day 2010, Issa told radio host Rush Limbaugh that Obama was “one of the most corrupt presidents in modern times.” He likened the Justice Department’s “Fast and Furious” gun-tracking program, in which weapons provided by undercover U.S. agents ended up linked to the killing of a Border Patrol agent, to the Watergate scandal that ended Richard M. Nixon’s presidency.

The gun probe did lead to a rare contempt citation issued to Holder, but to date none of Issa’s investigations, or any other GOP probe, has forced a Cabinet secretary out of office. No independent prosecutor has been appointed of the sort that hounded the previous four administrations. Democrats believe this is because Issa is drawn to headlines, chasing the hot story rather than committing himself and his staff to the long slog of digging through documents to uncover hidden information.

Issa and his aides insist they take a long view. “His three-year-long investigation into VIP mortgage deals that defunct lender Countrywide made to members of Congress and other connected officials even won rare praise from the New York Times editorial board. He led oversight efforts that assuaged GOP fears about the 2010 Census and help shepherd into law bipartisan whistleblower protection legislation that had stalled out in previous congresses,” said Frederick Hill, Issa’s spokesman.

In March, after reading a report in Roll Call newspaper that tea-party-linked groups had received extensive information requests from the IRS, Issa’s staff got in touch immediately with the Treasury Department’s inspector general to find out whether the tax agency was targeting conservative groups. He and Rep. Jim Jordan (R-Ohio), a senior committee member, confirmed in an exchange of letters last summer that the IG was investigating the matter — and last Friday, an apologetic IRS official stunned Washington with an admission that the agency had improperly targeted conservative groups.

Now, as GOP congressmen line up to demand resignations, Issa is playing coy, asserting that it’s not his place to determine who works for the president. Instead, he’s trying to hit the right notes about the integrity of his investigation, promising to following it wherever the evidence leads. The committee plans a May 22 hearing on the IRS controversy.

Tuesday evening, House Speaker John A. Boehner (R-Ohio) brought Issa into his daily leadership meeting to review last week’s Benghazi hearing. A Republican in the room, requesting anonymity to describe a closed-door huddle, portrayed Issa as “methodical, well-prepared and reasonable” — prompting Boehner and Majority Leader Eric Cantor (R-Va.) to praise Issa in front of more than 200 colleagues at Wednesday morning’s weekly GOP caucus.

Issa challenges the Democratic notion that he will overplay his hand. He says that he has gotten better at his job.

“My team is more mature this year than last Congress. Many of my members last Congress were freshmen. I was in my first term as chairman,” he told reporters Tuesday night. “If I’m better, it’s because my members are more matured in their job and my staff is doing a great job.”

Jordan said that in advance of last week’s hearing, Issa laid out the topics on which he wanted the first five or six Republicans to question the State Department witnesses, akin to how football coaches sometimes script the first 20 plays of a game in advance. GOP lawmakers were instructed to allow the witnesses to answer the questions and not to spend all their time posturing, as often happens at hearings.

The result was a news cycle focused almost entirely on what the witnesses said.

Administration officials dispute Issa’s maturity. In the days leading up to the Libya hearing, his committee posted on its Flickr photo account a series of promo shots that almost seemed to be hyping a Hollywood movie, with a star in between the words “Exposing Failure . . . Recognizing Courage.” Administration officials note that it was the Treasury inspector general for tax administration who exposed IRS misdeeds, not Issa, just as an inspector general last year unveiled wasteful spending on lavish conferences in places such as Las Vegas by the General Services Administration.

Issa is clearly relishing the moment. He has lived a dramatic life, a Frank Abingale story with an even better ending: That 1960s character, portrayed by Leonardo DiCaprio in “Catch Me If You Can,” served five years in prison for a massive counterfeiting scheme before helping federal investigators catch crooks and, eventually, becoming a millionaire in the anti-fraud industry.

Issa was a troubled youth outside Cleveland, accused but never convicted of stealing cars. He moved to California and become a multimillionaire building the Viper car alarm. He won his Southern California district in 2000 and, after several aborted attempts at statewide office, settled into the House as his longtime home. Always seemingly in a hurry, Issa had nowhere to go until a series of retirements by such veterans as Davis and losses by other Republicans thrust him to the top of the oversight committee.

Once investigated himself for possible crimes, Issa is now the House’s top investigator. Complete with the most extensive subpoena power of anyone on Capitol Hill.

“I’ll put out the facts and others will decide,” Issa said.

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