Both Democratic and Republican lawmakers called on Secret Service Director Kimberly Cheatle to step down in the wake of the assassination attempt of Donald Trump.

The demand came during and after a tense House Oversight Committee hearing on Monday that questioned Ms Cheatle about her agency's security preparations ahead of a 13 July rally in Butler, Pennsylvania, that led to the attempt on Trump's life.

The shooting left one person dead and three others wounded - including the former president.

Monday's hearing was bruising for Ms Cheatle, as lawmakers ridiculed her answers and the lack of information the agency had made public, but it was also a rare show of bipartisanship on an increasingly polarised Capitol Hill.

For nearly six hours, members sought to answer lingering questions about the shooting, including how suspect Thomas Matthew Crooks was able to get on to a nearby rooftop and why Trump was allowed to take the stage even after a suspicious person had been reported.

After the hearing, the leading Republican and Democrat from the committee - James Comer and Jamie Raskin - sent a letter to Ms Cheatle that concretely laid out their belief that she should vacate her office.

"In the middle of a presidential election, the Committee and the American people demand serious institutional accountability and transparency that you are not providing," the letter says. "We call on you to resign as Director as a first step to allowing new leadership to swiftly address this crisis and rebuild the trust of a truly concerned Congress and the American people."

While Ms Cheatle took responsibility during the hearing for the security lapses and acknowledged that the Butler incident marked "the most significant operational failure of the Secret Service in decades", she left many lawmakers frustrated.

Ms Cheatle pushed back on calls to resign and said she remained "the best person to lead the Secret Service at this time".

The Secret Service director also answered few questions directly - citing the ongoing investigation.

"The American people have questions, [and] they deserve answers," Oversight Committee Chairman Mr Comer told Ms Cheatle.

"You were required to provide answers and, ma'am, you did not."

At times, the tense hearing on Monday seemed to devolve into fury. Lawmakers used expletives, shouted at the witness and questioned the director's honesty and competence.

"I'm disgusted by your performance," Florida congresswoman Anna Paulina Luna said.

Ms Cheatle's answers seemed to continuously spark the ire of lawmakers on the committee, many of whom said she should be dismissed if she continued to refuse to resign.

"It looks like you won't answer some pretty basic questions," Ohio Republican Jim Jordan, a Trump ally, said. "And it looks like you cut corners when it comes to protecting one of the most well-known individuals on the planet."

Throughout the hearing, some representatives groaned loudly, rolled their eyes, or muttered audibly in response to Ms Cheatle's comments.

In one of the tensest moments of the hearing, South Carolina Republican Nancy Mace uttered a string of expletives in response to another one of Ms Cheatle's answers, specifically about how her opening remarks were leaked to US media outlets over the weekend.

"You are being dishonest or lying," Ms Mace said. "You're just dodging!" She later filed a congressional motion to impeach Ms Cheatle, to force her out of the job.

Another Republican, Georgia's Marjorie Taylor Greene, shouted at Ms Cheatle, referring to her as a "total failure".

"The entire country is demanding you resign," Ms Greene said.

Ms Cheatle also acknowledged that, to date, no Secret Service officers or employees have been disciplined for what took place in Butler.

According to Ms Cheatle, a preliminary report on the shooting will be released in the next 60 days - a timeline that committee members scoffed at.

New York's Alexandria Ocasio-Cortez, a Democrat, said that the delay of such a report during a tense election season was "not acceptable".

"This is not theatre, this is not about jockeying, this is about the safety of some of the most highly targeted and valued targets internationally and domestically," Ms Ocasio-Cortez said. There needs to be answers. We need to make policy decisions."

"Without that, we're flying blind," she added.

Despite the relative show of unity regarding Ms Cheatle's future, there were some points of disagreement between Republicans and Democrats on the committee.

Several Republicans, for example, characterised Ms Cheatle as a "DEI" - diversity, equity and inclusion - hire and questioned whether female agents assigned to Trump's security detail were able to do the job properly.

Others, such as Colorado's Lauren Boebert and Ms Luna of Florida, hinted at conspiracy theories that have appeared online.

Florida Republican Michael Waltz blamed Ms Cheatle for the rumours, arguing that misinformation "flies" in the absence of information.

"I would have fired you just by how you handled this," Mr Waltz said, "because you should have been the first to the mics."

Several eyewitnesses to the shooting in Butler told the BBC that Ms Cheatle's answers left them feeling frustrated and angry.

"She's trying to pass the buck," said Jean Vincent, a Butler resident. "I'm actually amazed at how insufficient her answers were. She needs to be held accountable for her total lack of competency... she put our lives at risk and needs to take responsibility."

Another witness, former US Marine Teresa Wilson, said that while she understands that there are active investigations still taking place, Ms Cheatle was far too "evasive".

"The only acceptable thing she could have done is take responsibility and step down," Ms Wilson said. "All the rest is noise."