Democrats in the House and Senate have proposed legislation that would provide free, lifetime identity protection to the millions of people who had their personal information stolen through the Office of Personnel Management.

It's not yet clear how much that proposal would cost, but based on OPM's recent mitigation efforts, it could easily climb into the hundreds of millions or even billions of dollars.

Sen. Ben Cardin, D-Md., and Del. Eleanor Holmes Norton, D-D.C., offered the bill last week, on the same day OPM announced that a total of 22.1 million people were hit in two separate data breaches. The Democratic members reacted immediately by saying lifetime coverage is needed.

"Private-sector cyberhacks and cyberattacks have become too commonplace, but when the federal government's own computer system shows its vulnerabilities to the world, we have a responsibility to protect the people who have been put at risk," Cardin said. "Off-the-shelf solutions are not good enough. We need to plug the holes in the federal network and make sure our workers, their families and all those who have been violated are held harmless from any damage that may be done."

A spokeswoman for Cardin said there was no estimate of how much it would cost to provide "comprehensive identity protection coverage" to all 22.1 million people. But OPM's initial steps to help the government workers and others hit in the attack shows the costs could quickly soar.

In June, OPM entered into a contract with a company that was tasked with reaching out to 3.2 million people by phone and email, and giving them 18 months of free credit monitoring and identity theft insurance. Those actions alone cost the government $20 million.

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Under the Democratic bill, nearly seven times as many people would be helped with free identity theft coverage, and that coverage would be "effective for the remainder of the life of the individual." In some cases, that could be several decades, as some of those hit were children of government workers.

The bill also specified that coverage would include "not less than $5,000,000 in identity theft insurance." That's five times higher than the $1 million OPM gave to the first 3.2 million affected workers.

Covering seven times as many workers, covering them for life instead of just 18 months, and giving them five times the level of protection than OPM's original offer seems to imply a total cost that would easily reach the hundreds of millions of dollars, and possibly into the billions of dollars by the time the proposed program ended.