The resignation came less than a day after lawmakers from both parties assailed Ms. Pierson’s leadership and said they feared for the lives of the president and others in the protection of the agency.
A 30-year veteran of the Secret Service, Ms. Pierson was supposed to have been the one to repair the agency’s reputation after scandals that raised questions about a culture that gave rise to incidents involving drinking and prostitution during overseas trips.
But her tenure has been rocked by more serious allegations that her agents and officers have not been performing their primary job competently. Under intense questioning on Capitol Hill on Tuesday, Ms. Pierson admitted that those charged with securing the White House had failed to follow numerous security protocols, allowing a man armed with a knife to penetrate deep inside the mansion.
