WASHINGTON — Secret Service Director Julia Pierson resigned Wednesday in the face of multiple revelations about bumbling in her agency and rapidly eroding confidence that the president and his family were being kept safe.

President Barack Obama "concluded new leadership of that agency was required," said White House spokesman Josh Earnest.

Though the day, high-ranking lawmakers from both parties had urged her to step down after her poorly received testimony to Congress a day earlier — and revelation of yet another security problem: Obama had shared an elevator in Atlanta last month with an armed guard who was not authorized to be around him.

"Today Julia Pierson, the director of the United States Secret Service, offered her resignation, and I accepted it," Homeland Security Secretary Jeh Johnson said in a statement. He announced that Joseph Clancy, retired head of the agency's Presidential Protective Division, would come out of retirement to lead the Secret Service temporarily.

Taking further steps to restore trust in the beleaguered agency, Johnson also outlined an independent inquiry into the agency's operations.

That trust was shaken by a series of failures in the agency's critical job of protecting the president, including a breach Sept. 19, when a knife-carrying man climbed over the White House fence on Pennsylvania Avenue and made it deep into the executive mansion before being stopped.

After a congressional hearing Tuesday into that breach and an earlier one, reports emerged of still another. Earlier in September, Obama had shared an elevator in Atlanta with a private guard who was not authorized to be around him with a gun. That was the first known Secret Service failure to unfold in the presence of the president. The first family was not at the White House when the recent intruder entered.

The White House learned about the Atlanta episode when lawmakers and the public did — when the Washington Examiner and The Washington Post reported it, Earnest said.

Obama had not been told about it previously, Earnest said. This, despite Pierson's statement to the committee that she briefs the president "100 percent of the time" about breaches to his personal security and those at the White House. She said the only time she had briefed him this year was after the Sept. 19 White House incident.

Support for Pierson unraveled quickly after her defensive testimony Tuesday, which left key questions unanswered.

Sen. Chuck Schumer, the No. 3 Senate Democrat, and Sen. Lindsey Graham, a Republican, were both to issue public calls for her resignation on Wednesday afternoon, their offices said. And Rep. Jason Chaffetz, a senior Republican on the House Oversight and Government Reform Committee, said Pierson should either resign or Obama should fire her.

"Unfortunately, the Secret Service director's appearance before the Oversight and Government Reform Committee has left us with more questions than answers," said House Speaker John Boehner, R-Ohio. Although he stopped short of calling for Pierson's resignation in a statement early in the day, he backed a call for an independent investigation and said, "The president must make a swift determination on whether the agency is being well-served by its current leadership."

Democratic Rep. Elijah Cummings, top Democrat on the committee, said in multiple interviews Wednesday that Pierson was no longer the best person to lead the Secret Service.

"There has to be accountability when that is not the case," added House Minority Leader Nancy Pelosi, who also backed calls for an independent investigation.