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U.S. Secret Service Director Kimberly Cheatle resigned Tuesday in the wake of mounting pressure following the assassination attempt on former President Trump, Fox News confirmed. 

Fox News reviewed the letter Cheatle sent to the U.S. Secret Service Tuesday morning, just a day after taking bipartisan heat during testimony before the House Oversight Committee Monday and over a week after a would-be assassin Thomas Crooks attempted to take the life of Trump at his rally in Butler, Pennsylvania, on July 13. 

"To the Men and Women of the U.S. Secret Service, The Secret Service’s solemn mission is to protect our nation’s leaders and financial infrastructure," Cheatle wrote in a letter to the agency. "On July 13th, we fell short on that mission."

Cheatle said that the "scrutiny" over the last week "has been intense and will continue to remain as our operational tempo increases." 

"As your Director, I take full responsibility for the security lapse," she wrote. 

Kimberly Cheatle testifies before the House Oversight and Accountability Committee

United States Secret Service Director Kimberly Cheatle announced her resignation after testifying before the House Oversight Committee, July 22, 2024, in Washington, D.C. (Justin Sullivan/Getty Images)

Biden, who did not fire Cheatle in the 10 days since the shooting, said he is "grateful to Director Kim Cheatle for her decades of public service," and that he will appoint a new director soon. 

"As a leader, it takes honor, courage, and incredible integrity to take full responsibility for an organization tasked with one of the most challenging jobs in public service," Biden said. "We all know what happened that day can never happen again. As we move forward, I wish Kim all the best."

Cheatle said, though, that the "incident does not define us." 

"We remain an organization based on integrity and staffed by individuals of exceptional dedication and talent," she wrote, adding that the agency "will move forward with our investigatory and protective mission in a steadfast manner." 

"We do not retreat from challenge," she wrote. "However, I do not want my calls for resignation to be a distraction from the great work each and every one of you do towards our vital mission." 

Cheatle said that when she got the call asking whether she would return to the Secret Service after her brief retirement from the agency, she said she "did not hesitate." 

"I love this agency, our mission, and the great men and woken who sacrifice so much every day," she wrote. "I have, and will always, put the needs of this agency first." 

"In light of recent events, it is with a heavy heart that, I have made the difficult decision to step down as your Director," Cheatle wrote. 

WATCH: Rep. Mace says Secret Service director 'full of s---' at hearing

Cheatle reflected on her career, reminding that she served as a special agent for 27 years, securing events for then-First Lady Hillary Clinton; worked as a supervisor on then-Vice President Dick Cheney's detail; supervised then-Vice President Biden's detail; lead RTC and more--including "overseeing the agency's protective mission under the Trump Administration as AD-OPO." 

"As I stated in the hearing yesterday, all of you are worthy of trust and confidence," Cheatle wrote. "You deserve the nation’s support in carrying out our critical mission."

Cheatle said "one of my favorite things about this workforce is that the men and women are fiercely committed to our mission." 

"Thank you for all that you do, and will continue to do, for our great nation," she wrote, signing the letter "kac." 

SECRET SERVICE EXPLANATION CONTINUES TO EVOLVE ONE WEEK AFTER ATTEMPTED ASSASSINATION

Trump, during his rally, ever-so-slightly turned his head—narrowly missing the bullet shot by 20-year-old suspect Crooks’ AR-15-style rifle by just a quarter of an inch. The bullet hit him, instead, in his upper right ear.

The bullet killed firefighter, father and husband Corey Comperatore as he protected his family from the shots, and severely injured two others. 

Cheatle admitted under oath that the Secret Service "on July 13th, we failed." 

"As the director of the United States Secret Service, I take full responsibility for any security lapse of our agency," she said. "We must learn what happened and I will move heaven and earth to ensure that an incident like July 13th does not happen again." 

Cheatle added: "Our agents, officers and support personnel understand that every day we are expected to sacrifice our lives to execute a no fail mission."

Donald Trump onstage at a rally

Secret Service tend to republican presidential candidate former President Donald Trump onstage at a rally on July 13, 2024 in Butler, Pennsylvania.  (Anna Moneymaker/Getty Images)

House Republicans, including House Oversight Committee Chairman James Comer, had been calling on Cheatle to resign, calling her and the agency under her watch "the face of incompetence." 

"It is my firm belief, Director Cheatle, that you should resign," Comer said during the hearing. "The safety of Secret Service protectees is not based on their political affiliation. And the bottom line is that under Director Cheatle’s leadership, we question whether anyone is safe." 

But Cheatle had defied those calls for days, maintaining she would not tender her resignation, and instead appeared before Congress to answer questions for the American people. 

SECRET SERVICE UNDER HOMELAND SECURITY INSPECTOR GENERAL INVESTIGATION AFTER TRUMP ASSASSINATION ATTEMPT

Cheatle’s initial explanation of why there was such a significant security lapse that led to the near assassination of Trump included details about the roof Crooks was perched upon. 

"That building in particular has a sloped roof at its highest point. And so, you know, there's a safety factor that would be considered there that we wouldn't want to put somebody up on a sloped roof," Cheatle said last week. "And so, you know, the decision was made to secure the building, from inside." 

U.S. Secret Service Director Kimberly Cheatle is sworn in to testify before the House Oversight and Accountability Committee about the attempted assassination of former President Donald Trump at a campaign event in Pennsylvania that also saw one rallygoer killed and two others seriously wounded, at the Capitol in Washington, Monday, July 22, 2024. AP Photo/J. Scott Applewhite

U.S. Secret Service Director Kimberly Cheatle is sworn in to testify before the House Oversight and Accountability Committee about the attempted assassination of former President Donald Trump at a campaign event in Pennsylvania that also saw one rallygoer killed and two others seriously wounded, at the Capitol in Washington, Monday, July 22, 2024. AP Photo/J. Scott Applewhite

During the hearing, Cheatle said the Secret Service is "still looking into the advanced process and the decision made" as to why an agent wasn't positioned on top of the roof that Crooks used to fire at former President Trump.

"The building was outside of the perimeter on the day of the visit. But again, that is one of the things that during the investigation, we want to take a look at and determine whether or not other decisions should have been made," she said. 

Thomas Matthew Crooks crawling on a roof moments before he attempted to assassinate former President Donald Trump.

Thomas Matthew Crooks crawling on a roof moments before he attempted to assassinate former President Donald Trump. (DJ Laughery (background))

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She added that "I'm not going to get into the specifics of the numbers of personnel that we had there, but we feel that there was a sufficient number of agents assigned" to the event.

Trump’s security detail reportedly asked for additional security from the Secret Service, repeatedly, but those requests were not met. 

The Department of Homeland Security's inspector general has opened an investigation into the Secret Service's handling of security for the Trump rally on July 13.