The size of the second breach exceeds most of the estimates previously reported in various media outlets.
The personnel agency said Thursday that it has not seen any indication that the stolen information has been "misused" or otherwise disseminated.
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On Wednesday, FBI Director James Comey refused to provide a specific number when asked by members of the Senate Intelligence Committee about the size of the breach. Comey did say the hack was "enormous," however, and confirmed that his own data had been compromised.
Several lawmakers in both parties have called for the resignations of Archuleta and Donna Seymour, the chief information officer at OPM, since the data breaches came to light last month. A rush of statements Thursday added to that growing chorus building against Archuleta, from House Speaker John Boehner, House Majority Whip Steve Scalise, and Republican Sens. John McCain and Marco Rubio, among others.
Sen. Mark Warner, who sits on the Senate Intelligence Committee and has been involved in the fallout following the OPM hacks, also called for Archuleta's ouster late Thursday.
"The technological and security failures at the Office of Personnel Management predate this director's term, but Director Archuleta's slow and uneven response has not inspired confidence that she is the right person to manage OPM through this crisis," the Virginia Democrat said in a Thursday night statement. "It is time for her to step down, and I strongly urge the administration to choose new management with proven abilities to address a crisis of this magnitude with an appropriate sense of urgency and accountability."
Rep. Barbara Comstock, a Virginia Republican who was notified last month that her personal information had been compromised in the hacks due to her previous roles as a federal employee, chided Archuleta for displaying "complacency, apathy "... and incompetence" in the wake of the breach.
"It goes to the top," Comstock said in an interview with National Journal. "This is a failure of leadership on her part, and if the president does not have the leadership to do this, I think she should step aside."
At least two House Democrats, Reps. Ted Lieu and Jim Langevin, the cochair of the House cybersecurity caucus, also have demanded Archuleta's removal. Lieu and Republican Rep. Steve Russell went a step further Thursday, announcing that they were working on legislation that would move the security-clearance database out of OPM entirely and into the hands of an unspecified agency "that has a better grasp of cyberthreats."
Archuleta, for her part, has remained resolute in the face of withering scrutiny. During a Thursday press call, the onetime political director for President Obama's 2012 reelection campaign, said she and her staff should be applauded, not condemned, for their efforts to upgrade the agency's cybersecurity since she took office in November 2013.