Kimberly Cheatle says the incident is ‘the most significant operational failure at the Secret Service in decades’.

The US Secret Service chief has admitted to Congress that the agency failed to prevent the attempted assassination of former President Donald Trump at a July 13 campaign rally in Butler County, Pennsylvania.

“We failed. As the director of the United States Secret Service, I take full responsibility for any security lapse,” Director Kimberly Cheatle, who faces Republican calls for her removal, said on Monday in testimony before the Committee on Oversight and Accountability in the US House of Representatives.

“The assassination attempt on former President Donald Trump on July 13 is the most significant operational failure at the Secret Service in decades,” Cheatle said.

“There clearly was a mistake and we will make every effort to make sure that this never happens again,” she said.

The shooting at an outdoor campaign rally wounded Trump in the right ear, killed one rally attendee and injured two others.

The suspected shooter, 20-year-old nursing home aide Thomas Matthew Crooks, was killed by law enforcement. The motive for the shooting is not clear.

Cheatle said Crooks had been identified as “suspicious” before Trump took the stage but had not been deemed to be a “threat”.

Cheatle ‘dodged’ many questions

Bob Ayers, a former CIA officer and international security analyst, told Al Jazeera that Cheatle “dodged” many of the questions the committee asked her.

“I was in Washington for 20 years, and I’ve even testified before the Senate … when you go before a congressional committee of any sort, you are briefed to no end by your staff,” he said, adding that Cheatle “walked in like she didn’t know what was going to be asked, and so she tried to stonewall”.

Al Jazeera’s Shihab Rattansi, reporting from Washington, DC, said that despite evading many of the questions, Cheatle did provide some information.

“She did confirm that the FBI had informed the Secret Service that the gunman had used a drone in the area”, as well as that he had brought in a range finder – a small device to measure distance – that wasn’t a prohibited item, Rattansi said.

In the face of Republican accusations that the Secret Service, the agency responsible for protecting current and former presidents, has denied resources to protect Trump, she said security for the presidential candidate had grown before the shooting.

“The level of security provided for the former president increased well before the campaign and has been steadily increasing as threats evolve,” Cheatle said. “Our mission is not political. It is literally a matter of life and death.”

Monday’s hearing marked the first round of congressional oversight of the attempted assassination.

On Wednesday, FBI Director Christopher Wray will appear before the House Judiciary Committee.

House Speaker Mike Johnson is also due to unveil a bipartisan task force to serve as a nexus point for House investigations.

Cheatle has resisted calls for her resignation from top Republicans, including Johnson and Senate Minority Leader Mitch McConnell.

House Committee on Oversight and Accountability Chairman James Comer, a Republican, echoed those calls at the hearing.

“It is my firm belief, Director Cheatle, that you should resign,” the Kentucky lawmaker told her.

“The Secret Service has thousands of employees and a significant budget. But it has now become the face of incompetence.”

Democratic US Representative Gerry Connolly said, “Unacceptable incidents like this one highlight the fact that we are an increasingly polarised nation experiencing heightened political tensions.”