The 30-second spot, titled “Admit,” is the latest move by Clinton’s campaign to highlight McCarthy’s remark, made last week on Fox News, which her team claims is proof that the Benghazi probe was set up to destroy Clinton’s campaign.
The ad, a small, five-figure national cable TV buy, uses McCarthy’s comment to make the campaign's larger point that Republicans are on a mission to bring down Clinton.
"Everybody thought Hillary Clinton was unbeatable, right, but we put together a Benghazi special committee," McCarthy can be heard saying. After a cut in the tape, the contender for House Speaker says: "What are her numbers today?"
McCarthy later said the Benghazi committee had "nothing to do with politics." "This committee was set up for one sole purpose: to find the truth on behalf of the families of four dead Americans," he said on Fox News.
The California Republican defended the committee in a response to the ad Tuesday morning, describing its work as "beyond reproach."
"The serious questions Secretary Clinton faces are due entirely to her own decision to put classified information at risk and endanger our national security," he said in the statement.
In a statement, a rep for House Speaker John Boehner blasted the spot.
"This is a classic Clinton attempt to distract from her record of putting classified information at risk and jeopardizing our national security, all of which the FBI is investigating," said Boehner spokeswoman Emily Schillinger.
Clinton, who has drawn scrutiny for the Benghazi attack and using a private email server to conduct government business, has maintained that she did nothing illegal.
According to Clinton's campaign, the spot is part of a new national cable TV ad buy that begins on Tuesday.
Since August, Clinton has aired several television ads across the early voting states of Iowa and New Hampshire. This new ad will be the first one to air nationwide, according to a campaign official. It is expected to air on the cable news outlets, CNN and MSNBC.
So far, Clinton’s campaign has spent roughly $14 million for air space in Iowa and New Hampshire.
Clinton, however, was quick to defend herself as the national frontrunner. When asked about the New Hampshire poll in an interview with NBC News on Monday, she interjected.
“And it shows me winning in Iowa, South Carolina, Nevada and nationally,” she said, defensively. “So I'm happy to be in New Hampshire to talk to the people here."
The same poll does show Clinton ahead of Sanders in Iowa, but only by a slim margin: 33 - 28.