US Secret Service director Kim Cheatle has resigned from her position as head of the agency following the assassination attempt on former President Donald Trump.
Ms Cheatle testified for nearly six hours during a contentious House committee hearing on Monday.
Lawmakers became increasingly frustrated when she refused to answer questions about the shooting at Trump's campaign rally in Butler, Pennsylvania earlier this month.
"As your Director, I take full responsibility for the security lapse," she said in her resignation letter on Tuesday.
Both Democrats and Republicans had called for her to step down.
In the letter to staff, Ms Cheatle said she has always "put the needs of the agency first" and it is “with a heavy heart” that she made her decision.
“The scrutiny over the last week has been intense and will continue to remain as our operational tempo increases,” she said.
“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.”
President Joe Biden said in a statement that he's grateful for her decades of public service.
"The independent review to get to the bottom of what happened on July 13 continues, and I look forward to assessing its conclusions. We all know what happened that day can never happen again," he said.
Mr Biden said he will appoint a new director soon.
The president appointed Ms Cheatle to head the Secret Service in 2022. She had previously served 27 years at the agency in various roles.
The shooting at the 13 July rally left one audience member dead and two others wounded. A bullet grazed the former president's ear.
"The Biden/Harris Administration did not properly protect me, and I was forced to take a bullet for Democracy," Trump posted on his social media platform in response to the news of her resignation.
Lawmakers questioned Ms Cheatle about security preparations ahead of Trump's campaign rally during the tense House Oversight Committee hearing on Monday.
Ms Cheatle took responsibility for the security lapses, but pushed back on calls to resign.
She called the shooting "the most significant operational failure at the Secret Service in decades".
Witnesses reported seeing a suspicious man - suspect Thomas Matthew Crooks - with a rifle on a rooftop at the rally minutes before shots were fired.
Crooks was killed by a counter sniper shortly after.
Ms Cheatle didn't offer lawmakers any new information on how Crooks was able to access the roof where he was perched and why Trump was allowed to take the stage.
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After the hearing, the leading Republican and Democrat from the committee - James Comer and Jamie Raskin - sent a letter to Ms Cheatle that laid out their belief that she should step down.
Mr Comer said Ms Cheatle “instilled no confidence” during the hearing that she can fulfill the Secret Service’s protective mission.
“The Oversight Committee’s hearing resulted in Director Cheatle’s resignation and there will be more accountability to come,” he said in a statement posted on X, formerly Twitter.
Republican House Speaker Mike Johnson called her resignation “overdue” and said he is "glad she did the right thing".
"Now we have to pick up the pieces, we have to rebuild the American people's faith and trust in the Secret Service," he told reporters on Tuesday.