By Mark Hosenball and Roberta Rampton
WASHINGTON (Reuters) - U.S. Office of Personnel Management chief Katherine Archuleta resigned on Friday, a day after the Obama administration said massive computer hacks at the government agency had put the personal data of more than 21 million people at risk.
The White House, facing harsh criticism from Republicans in Congress, said Archuleta had stepped down and that OPM was stepping up cyber security measures, such as limiting the number of "privileged users" of computer data.
"I conveyed to the president that I believe it is best for me to step aside and allow new leadership to step in," Archuleta said in a statement.
The latest hacking revelation at OPM is in addition to one affecting data about 4.2 million current and former federal workers that was stolen in what the OPM called a "separate but related" hacking incident.
Because many of the same people were affected by both hacks the total comes to 22.1 million people. That means almost 7 percent of the U.S. population was susceptible to personal data theft in one of the most damaging cyber security breaches ever.
Beth Cobert, currently working in the White House budget office, will assume the role of acting director of the personnel office. Archuleta's resignation will be effective at the end of Friday, the White House said.
Her departure was not expected to solve the agency's technological problems, but congressional overseers said it was a step in that direction.
Social Security numbers and other sensitive information was stolen from OPM databases in the sweeping computer intrusions.
The United States has identified China as the leading suspect in the hacking of the U.S. government agency, but China's Foreign Ministry has dismissed that as "absurd logic."
Archuleta's departure comes a day after House of Representatives Speaker John Boehner, a Republican, issued a statement saying that he had "no confidence" in OPM's current leadership.
On Friday, Boehner, citing chronic problems at the Veterans Administration that led to the resignation of Secretary Eric Shinseki last year, said "a change in personnel does not always lead to real change" and Obama must "repair" the problem at OPM.
Archuleta, who was a high-ranking official in Obama's 2012 re-election campaign, also was criticized by some Democrats. Senator Mark Warner on Thursday accused her of a "slow and uneven response" to the data breach.
Obama appointed Archuleta to the top OPM job in May 2013 and she was sworn in the following November, becoming the first Latina to head the federal agency.
The computer hacks at OPM, coupled with computer glitches this week that disrupted operations at both the New York Stock Exchange and United Airlines, have raised serious concerns in Congress that the federal government needs to do more to improve and safeguard computer systems.
(Additional reporting by Lisa Lambert; Editing by Kevin Drawbaugh and Tom Brown)