Cheatle's resignation follows the massive outcry over the agency's failure to protect the former President during the assassination attempt at the Pennsylvania campaign.

In an email sent to the staff on Tuesday, she said, "I take full responsibility for the security lapse," adding that, "In light of recent events, it is with a heavy heart that I have made the difficult decision to step down as your director.”

However, Cheatle's resignation is less likely to end the scrutiny of the long-troubled agency after the failures of July 13. Lawmakers on both sides have promised continued investigation.

“The scrutiny over the last week has been intense and will continue to remain as our operational tempo increases,” Cheatle said in her note to staff.

Cheatle, who has been serving as the Secret Service director since August 2022, was being asked to resign amid the agency's lapse in protecting the Republican presidential candidate.

Calls for several investigations into how the shooter was able to get so close to Trump at an outdoor campaign rally.

Earlier in the day, at the House Oversight Committee hearing, Kimberly Cheatle agreed that it was a "colossal failure" on the Secret Service's part, adding that it was a tragedy that could have been prevented.

Republican Representative Nancy Mace blasted Cheatle and said that she was being "dishonest" and that her statements was "bulls***".

At the Trump rally shooting hearing, lawmakers of both major political parties had demanded that Cheatle resign from the post of Secret Service's Director over the security failures that let a gunman to scale a roof and open fire at a campaign rally.

Both the Republicans and the Democrats grilled the Secret Service chief for hours at the House Oversight Committee hearing.

Cheatle herself said that it was their "most significant operational failure" in decades and promised to "move heaven and earth" to get to the bottom of what went wrong and make sure that this doesn't happen again.

"The Secret Service's solemn mission is to protect our nation's leaders. On July 13, we failed," she told the committee.

Reportedly, Kimberly had said that she had spoken to Trump over a phone call after the assassination attempt and conveyed her apologies.

And while she took full responsibility for the security lapses at the hearing, Cheatle had asserted that she was the "right person" to lead the Secret Service.

Republican chairman, Rep. James Comer and the Committee's top Democrat, Rep. Jamie Raskin, issued a letter calling for Cheatle's resignation.

Two days ago, in an interview with ABC News, Cheatle had said that he was not resigning. Terming the shooting to be "unacceptable", she said that this was something no Secret Service agent wants to happen.

She said her agency is responsible for the former president's protection, “The buck stops with me. I am the director of the Secret Service.”

Notably, the 20-year-old shooter -- Thomas Matthew Crooks -- who was able to get within 135 metres of the stage where the former President was speaking, was shot dead in retaliation after he opened fire at Trump.

Crooks, who fired six to eight shots, however managed to injure Trump and two other rallygoers and killed a 50-year-old supporter of the former President.

WHO IS KIMBERLY CHEATLE?

Kimberly Cheatle has served in the Secret Service for 27 years. She had left the job in 2021 for another job as a security executive at PepsiCo before US President Joe Biden asked her to return in 2022.

She had taken over at a time when there was a controversy over the missing text messages from around the time thousands of Trump supporters had stormed the US Capitol in January, 2021.

During her service in the agency, Cheatle was the first woman to be named assistant director of protective operations, the division which protects the President and other dignitaries where she supervised a $133.5 million budget.

Kimberly Cheatle is the second woman to the lead the agency in the entirety.

Biden, at the time of announcing her announcement, had said that Cheatle had served on his detail when he was the Vice President, adding that he and his wife "came to trust her judgment and counsel".