"They show -- from the inside -- that Kevin McCarthy's stark admission was true: Republicans have been abusing millions of taxpayer dollars for the illegitimate purpose of damaging Hillary Clinton's bid for president," Cummings said in a statement. "These are extremely serious whistleblower charges by one of Chairman Gowdy's own handpicked investigators."

Clinton's lead over Sanders shrinks as her edge over GOP vanishes

Podliska, an Air Force reservist who describes himself as a "conservative Republican" and who served 10 months as an investigator with the committee's majority staff before he was fired, told CNN in an interview that he believes the GOP-led investigation is "partisan." He said the inquiry's focus shifted to Clinton after the revelation in March that she used a private email server to conduct official business during her time as secretary of state.

While Clinton's spokesman said the allegations proved the investigation had been focused on Clinton "from the start," Podliska has insisted the inquiry began as a true fact-finding mission.

He is planning to file a lawsuit next month alleging that he was fired in part because he resisted pressure to conduct a skewed investigation focused exclusively on Clinton. He also alleges he was fired because he had to take time off for his military reserve duty.

The Benghazi Committee chairman Trey Gowdy denied Podliska's claims in a statement Sunday, in which he said the former employee never mentioned his concerns regarding the investigation. Gowdy again defended the mission of the committee as "the final, definitive accounting" of the Benghazi terrorist attacks and denied that its members were focusing on the former secretary of state.

"Because I do not know him, and cannot recall ever speaking to him, I can say for certain he was never instructed by me to focus on Clinton, nor would he be a credible person to speak on my behalf," Gowdy said in the statement. "I am equally confident his supervisor, General (Retired Lt. Gen. Dana) Chipman, did not direct him to focus on Clinton."

A spokesperson for the committee rejected Podliska's allegations and said in a statement that the former investigator was fired in part because of his own bias targeting members of the Obama administration -- a claim Podliska's attorney forcefully denied.

"We are confident that the facts and evidence give no support to the wild imagination fueling these and any future allegations, and the Committee will vigorously defend itself against such allegations. The Committee will not be blackmailed into a monetary settlement for a false allegation made by a properly terminated former employee," the committee spokesperson, who declined to be named, said in a statement to CNN on Saturday.

Other Republicans defended the committee's work Sunday. Rep. Raul Labrador, R-Idaho, told CNN's "State of the Union" that he faulted President Barack Obama's administration and Clinton, who he said "decided a few months before an election that they were going to lie about what happened in Benghazi."

Rep. Tom Cole, R-Oklahoma, pointed to Gowdy's refusal to appear in regular media interviews as evidence that the committee's work isn't for political gain.

"Until the last couple of weeks, most of the attacks on this committee have come from the right because it was seen as being too judicious and not partisan," Cole said on "State of the Union."

Other Democrats were also quick to seize on Podliska's accusations.

The House Intelligence Committee's top Democrat, Rep. Adam Schiff, and the ranking Democrat on the House Armed Services Committee, Rep. Adam Smith, renewed calls Saturday to shut down the committee.

"Even before Kevin McCarthy's comments laid bare the true intent of the committee, it's been clear that Secretary Clinton has been the true target of this investigation, and the Republican whistleblower who has come forward only provides further evidence of what has been long evident. It's time to shut down the Benghazi Select Committee," Schiff said in a statement.

Smith said "there should no longer be any doubt as to why the committee was created."

"If the allegations articulated by the investigator, who was handpicked by Gowdy, are true then we should slam the door shut on this ugly chapter in American history and close down the Benghazi Committee," Smith said in a statement.

Podliska, though, told CNN that he does not want the committee to be disbanded. Instead, he said the committee needs to refocus its work on a broad, objective investigation of the circumstances surrounding the death of four Americans, including U.S. Ambassador Christopher Stevens, in the attacks on the U.S. consulate in Benghazi.

"Hillary Clinton has a lot of explaining to do. We, however, did not need to shift resources to hyper focus on Hillary Clinton. We didn't need to de-emphasize and in some cases drop the investigation on different agencies, different organizations and different individuals," Podliska said.

David Brock, the founder of the pro-Clinton Correct the Record organization, called the committee's investigation "a political witch hunt.

"If Republicans were smart, which is debatable, they would end this farce before it does even more damage to them than it already has," Brock said in a statement.