Updated

A top Capitol Hill Democrat suggested Sunday that the Republican-led House committee leading probes into controversial Obama administration activities is squashing testimony in the recent IRS scandal and taking an overall “accuse, then prove” approach to investigations.

The House Committee on Oversight and Government Affairs has released closed-door testimony that indicates two Cincinnati IRS field agents were directed by Washington officials to target Tea Party groups applying for tax-exempt status.

However, Maryland Rep. Elijah Cummings, the committee’s highest-ranking Democrat, says the body won’t release a transcript in which a self-described "conservative Republican" IRS manager tells investigators that nobody at the White House directed the tax collection agency to target Tea Party groups or other politically conservative organizations.

In the partial transcript, the unidentified manager said he or she was unaware of any political motivation in giving extra scrutiny to the groups.

The manager was interviewed Thursday and says workers in Cincinnati initiated review of the applications, starting in 2010.

The manager also identifies him or herself as a “conservative Republican,” but says he or she never worked for such a candidate nor contributed to such a campaign, according to the 15-page staff memo that Cummings released and includes the partial transcript.

“I do not believe that the screening of these cases had anything to do other than identifying issues that needed to have further development,” the screening manager says in the transcript.

Cummings also sent a five-page letter to committee Chairman Darrell Issa, accusing the California Republican of withholding information in the IRS probe and criticizing how he has investigated the Justice Department’s flawed gun-tracking program Operation Fast and Furious, the fatal Benghazi terror attacks last year, and now the IRS.

“Your actions over the past three years do not reflect a responsible, bipartisan approach to investigations,” Cummings wrote. “And the committee’s credibility has been damaged as a result. Your approach in all of these cases has been to accuse first, and then go in search of evidence to back up your claims. … You have selectively leaked excerpts of interview transcripts, documents and other information, and you have withheld evidence that directly contradicts your claims.”

Issa responded to Cummings’ allegations and his comment Sunday on CNN’s “State of Union” that the IRS case is “solved” and that he would “wrap this case up” and move on.

"I strongly disagree with … Cummings' assertion that we know everything we need to know,” Issa said in a statement. “His extreme and reckless assertions are a signal that his true motivation is stopping needed congressional oversight and he has no genuine interest in working, on a bipartisan basis, to expose the full truth.”