 -- Embattled Office of Personnel Management Director Katherine Archuleta has resigned, officials said today.

White House Press Secretary Josh Earnest told reporters that Archuleta resigned "on her own volition."

"I think what the president thinks is that it’s quite clear that new leadership with a set of skills and experiences that are unique to the urgent challenges that OPM faces are badly needed," he said.

Archuleta is stepping down after the personal information of more than 22 million people was compromised in devastating hacks. That number is more than five times larger than what the Office of Personnel Management announced a month ago when first acknowledging a major breach had occurred.

At the time, OPM disclosed that the personnel records of 4.2 million current and former federal employees had been compromised. Investigators ultimately determined that 19.7 million applicants for security clearances had their Social Security numbers and other personal information stolen and 1.8 million relatives and other associates also had information taken, according to OPM. That includes 3.6 million of the current and former government employees for a total of 22.1 million.

In a letter to OPM staff after submitting her resignation this morning, Archuleta wrote that leading OPM was the "highlight of my career."

"I offered and the President accepted my resignation as the Director of the U.S. Office of Personnel Management," she wrote. "I am honored to have led this organization and to have served alongside you."

Archuleta is the third high-profile female official in the Obama administration to resign, following former Secret Service Director Julia Pierson in October 2014, and former Drug Enforcement Agency Director Michele Leonhart in April of 2015.

She told reporters Thursday that she had no immediate plans to step down, but there were mounting calls from Members of Congress on both sides of the aisle for the president to fire her.

The day after calling on President Obama to dump Archuleta, House Speaker John Boehner, Majority Leader Kevin McCarthy, Whip Steve Scalise and Republican Conference Chair Cathy McMorris Rodgers noted that her resignation “does not in any way absolve the president of the responsibility to repair this damage to our national security.”

“We know from last year’s resignation of the VA secretary that a change in personnel does not always lead to real change,” the quartet stated, adding a pledge to “hold the president accountable for restoring the public’s confidence.”

Archuleta was appointed by President Obama to serve as OPM director in May 2013. She previously served as political director of his reelection campaign in 2012. She will be replaced temporarily by Beth Cobert, the deputy director of the Office of Management and Budget, until a new director is appointed.