When Kimberly Cheatleled the Secret Service’s operations to safeguard the American president and other dignitaries, she said she would talk to agents in training about the “awesome responsibility” of their job.

“This agency and the Secret Service has a zero fail mission,” Cheatle, who is now director of the agency, said in 2021 during a Secret Service podcast called “Standing Post.” “They have to come in every day prepared and ready with their game face on.”

Now, the Secret Service and its director are under intense scrutiny over that “zero fail” mission following an assassination attempt on former President Donald Trump during a July 13 rally in Pennsylvania that wounded his ear. Lawmakers and others across the political spectrum are questioning how a gunman could get so close to the Republican presidential nominee when he was supposed to be carefully guarded.

Adding to that scrutiny is the agency’s acknowledgment late Saturday that it had refused to grant some of the Trump campaign’s requests for added security at his events, after initially denying that it had done so.

Cheatle, who will testify before lawmakers Monday after congressional committees and the Biden administration launched a series of investigations, told ABC News that the shooting was “unacceptable.” When asked who bears the most responsibility, she said ultimately it is the Secret Service that protects the former president.

“The buck stops with me,” Cheatle said. “I am the director of the Secret Service.” She said she has no plans to resign, and so far she has the administration’s backing.

Democratic President Joe Biden appointed Cheatle in August 2022 to take over an agency with a history of scandals, and she worked to bolster diverse hiring, especially of women in the male–dominated service. The second woman to lead the Secret Service, Cheatle worked her way up for 27 years before leaving in 2021 for a job as a security executive at PepsiCo. Biden brought her back.

Now, she faces her most serious challenge: figuring out what went wrong with the agency’s core responsibility to protect presidents and whether she can maintain the support — or the job itself — to make changes.

Details are still unfolding about signs of trouble the day of the assassination attempt, including the steps taken by the Secret Service and local authorities to secure a building that the shooter, Thomas Matthew Crooks, climbed within an estimated 147 yards of where Trump was speaking. An ex–fire chief at the rally, Corey Comperatore, was killed and two others were wounded.

The Biden administration has directed an independent review of security at the rally. The Homeland Security Department’s inspector general has opened three investigations and congressional committees have launched others as calls mount for Cheatle to resign. Two Republican senators demanding answers followed her as she walked through the Republican National Convention this past week.

“The nation deserves answers and accountability,” Senate Minority Leader Mitch McConnell, R–Ky., posted on the social media platform X. “New leadership at the Secret Service would be an important step in that direction.”

House Speaker Mike Johnson, R–La., said on X that Biden should fire Cheatle immediately, noting Comperatore’s death and saying that “we … were millimeters away from losing President Trump. It is inexcusable.” Rep. Brendan Boyle, D–Pa., said in a statement Saturday that ”the evidence coming to light has shown unacceptable operational failures” and he would have no confidence in Cheatle’s leadership if she were to stay in the job.