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Secret Service Director Kimberly Cheatle opened her testimony to Congress with a frank admission that her agency "failed" in its mission to protect former President Trump.

Cheatle testified before the House Oversight Committee on Monday, facing a grilling from Republican and Democratic lawmakers alike. Several GOP lawmakers have called on her to resign, though she has so far refused.

"The Secret Service's solemn mission is to protect our nation's leaders. On July 13, we failed," Cheatle said in her opening statement. "As director of the United States Secret Service, I take full responsibility for any security lapse of our agency. We are fully cooperating with ongoing investigations. We must learn what happened, and I will move heaven and earth to ensure that an incident like July 13th does not happen again."

Despite saying that she takes full responsibility for what happened, Cheatle has said she will not resign, stating during the hearing that she believes she is currently the best person to lead the Secret Service right now.

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Kimberly Cheatl

Secret Service Director Kimberly Cheatle opened her testimony to Congress with a frank admission that her agency "failed" in its mission to protect former President Trump. (Tierney L. Cross/Bloomberg via Getty Images)

Cheatle made clear that none of her testimony should be understood as a criticism of local law enforcement or other security partners the Secret Service worked with at former President Trump's rally in Butler, Pennsylvania.

Chairman James Comer, R-Ky., opened his questioning by asking whether a Secret Service agent had been on the roof the shooter used at any point on the day of the rally.

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Cheatle skirted the question, however, saying she could not offer specific details due to ongoing investigations. Comer then pressed about whether the building was within the security perimeter around Trump's rally, to which Cheatle said it was not.

Representative James Comer during a hearing in Washington, DC

Representative James Comer, a Republican from Kentucky and chairman of the House Oversight and Accountability Committee, speaks during a hearing in Washington, D.C., on Monday, July 22, 2024. The Secret Service's embattled leader pledged cooperation with all investigations into the agency after the attempted assassination of former President Trump. (Tierney L. Cross/Bloomberg via Getty Images)

Cheatle later confirmed to Rep. Jamie Raskin, D-Md., ranking member of the committee, that shooter Thomas Matthew Crooks was identified as a suspicious individual before Trump was taken onto the stage. He pressed Cheatle on why Trump was allowed on the stage despite the risk, and the official stated that while Crooks had been identified as suspicious, he had not yet been determined to be a threat.

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Representative Jamie Raskin during a hearing in Washington, DC

Rep. Jamie Raskin, a Democrat from Maryland and ranking member of the House Oversight and Accountability Committee, during a hearing in Washington, D.C., on Monday, July 22, 2024. The Secret Service's embattled leader pledged cooperation with all investigations into the agency after the attempted assassination of former President Trump. (Tierney L. Cross/Bloomberg via Getty Images)

Cheatle will spend several hours fending off questions from lawmakers throughout Monday's hearing. Comer set the tone for the day with his own opening remarks, in which he called on the director to resign.

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"It is my firm belief, Director Cheatle, that you should resign. However, in complete defiance, Director Cheatle has maintained she will not tender her resignation," Comer said in his remarks. "Therefore, she will answer questions today from members of this committee seeking to provide clarity to the American people about how these events were allowed to transpire."