Head of hacked gov't agency says she won't step down

Despite calls for the removal of the chief of the federal Office of Personnel Management in the wake of a new report on a recent hack on government computers, Katherine Archuleta says she will not resign, reports CBS News correspondent Major Garrett.

Sen. Mark Warner (D-Virginia), a White House ally, says Archuleta must go, and other Democrats call the data breach devastating and unacceptable. Now, eyes are on President Obama to see if he will fire her.

McCaul: OPM data hack “most significant” government breach ever

The scope of the hack is worse than first thought.

The Social Security numbers of 19.7 million Americans subjected to federal background checks as a condition of employment are now in the hands of hackers. Another 1.8 million Americans had their Social Security numbers stolen simply because they were listed as family members or friends of those applicants.

Chinese hackers are the chief suspects, but the Obama administration has not blamed China or anyone else.

"There's a huge counterintelligence risk. The Chinese will use this to spy on us," Center for Strategic and International Studies cybersecurity analyst James Lewis said. "This gives them an immense intelligence advantage."

The security breach also yielded home addresses, education and employment history, mental health, criminal and financial records. And investigators said hackers stole more than 1 million fingerprints.

What can the U.S. do to combat cyber hacks from China?

"They'll find a million ways to use this and none of them will be good for the U.S." Lewis said.

Sen. Cory Gardner (R-Colorado) said he's tired of waiting for the administration to name names.

"If the administration knows who did this, if they're certain, they ought to talk about it," Gardner said.

In the meantime, millions of Americans have received letters notifying them their information is at risk and referring them to a government-contracted credit-monitoring agency. There is no evidence, the government says, hackers have exploited the data for identity theft or other financial crimes.

But that could still happen, and intelligence experts said this trove of data, if used by a hostile government like China, could create spies who are harder to detect and who could pressure Americans to become spies, or could be used to stop activities that government opposes.