Office of Personnel Management Director Katherine Archuleta announced Friday she is resigning just one day after new revelations emerged that last month's massive federal data breach in the U.S. government was even worse than expected.

In June, the U.S. Office of Personnel Management, or OPM, revealed that hackers compromised personal data on 4 million government employees, marking the largest cyber-attack in U.S. history. According to OPM, the breach included records on 750,000 Department of Defense civilian personnel. Also included in those files were names, addresses, family members, education, Social Security numbers, security clearances and medical records.

However, on Thursday, it was revealed that the total number of people affected by the hack was over 22 million.

"I conveyed to the president that I believe it is best for me to step aside and allow new leadership that will enable the agency to move beyond the current challenges and allow the employees at OPM to continue their important work," Archuleta said in a statement, reports NBC News.

White House Press Secretary Josh Earnest confirmed at a press briefing that Archuleta resigned on "her own volition."

"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," Earnest said.

Following the hack, the Obama administration urged the Republican-controlled Congress to pass new cyber security rules. 

"The fact is, we need the United States Congress to come out of the dark ages and come into the 21st century to make sure we have the kinds of defenses that are necessary to protect a modern computer system," said Earnest on Friday, urging Congress to approved the stalled legislation, according to Yahoo News.

"Congress must take action," to speed notifications on breaches and increase cooperation between the government and private companies, added Senate Intelligence Committee vice chairman Dianne Feinstein.