CNN  — 

Hillary Clinton has joined the chorus of Democrats knocking House Majority Leader Kevin McCarthy’s suggestion that the House’s investigation into the 2012 terrorist attack in Benghazi was paying off politically.

In an interview with MSNBC’s Al Sharpton that will air on Sunday, Clinton said she finds McCarthy’s comments “deeply distressing,” adding that McCarthy showed “unequivocally” that the committee “was always meant to be a partisan political exercise.”

“I feel like it does a grave disservice and dishonors not just the memory of the four that we lost, but of everybody who has served our country,” Clinton said. “I really regret the way that they have treated this serious matter.”

Speaking with Fox News on Tuesday night, McCarthy – considered the leading candidate to replace outgoing House Speaker John Boehner – described the effects of the Benghazi Select Committee, a group ostensibly formed to look into the deaths of four Americans in 2012, as a political success.

“Everybody thought Hillary Clinton was unbeatable, right? But we put together a Benghazi special committee. A select committee. What are her numbers today? Her numbers are dropping. Why? Because she’s untrustable. But no one would have known that any of that had happened had we not fought to make that happen,” McCarthy said.

Democrats jumped on the comments Wednesday – Rep. Elijah Cummings, the committee’s top Democrat, called them a “stunning concession” – but Republicans also faulted their majority leader.

“I might have said it differently,” Rep. Darrell Issa, R-California, told CNN. “Any ancillary political activity that comes out of it is, in fact, not the goal of the committee and is not what the committee is seeking to do.”

Republican Rep. Justin Amash of Michigan said, “I totally disagree with those comments.”

CNN reached out to McCarthy’s office for further comment but did not immediately receive a response.

The House Benghazi Committee was formed in May 2014 and since has become one of the longest-running investigative committees in House history. Although it at first focused on the terrorist attack, the committee has somewhat changed its focus since discovering that Clinton exclusively used a private email server during her time at State.

Clinton will testify before the committee on October 22.

Clinton’s favorablity numbers have fallen since the Benghazi committee has been organized. A CNN poll released in August found Clinton’s favorability underwater, with 44% of people viewing her favorably and 53% viewing her unfavorably.

CNN’s Manu Raju contributed to this report.