States facing a federal deadline in May to launch a controversial program to tighten security requirements for driver's licenses got another reprieve Friday when the Department of Homeland Security delayed for the third time enactment of the 2005 law by 21 months to January 2013.

Homeland Security officials said the deadline was extended because most states would not be able to meet all the federal requirements of the so-called Real ID Act by May 11, partly because of the economic downturn and uncertainty about congressional action on a proposal to modify the law.

The regulations laid out in the law -- a recommendation of the Sept. 11 commission that investigated the 2001 terror attacks -- creates a national security standard for state-issued identification cards and driver's licenses to be used for federal purposes, like boarding a plane or entering federal buildings such as a courthouse.

The law aims to prevent terrorists from obtaining valid driver's licenses and ID cards. But the Bush administration delayed the program's original May 2008 compliance deadline amid claims that it was an unfunded federal mandate that would cause major disruptions in air travel and trample on Americans' privacy rights. The program is estimated to cost $11 billion over five years.

The Obama administration delayed a December 2009 deadline for compliance and tried to replace the law with a new program called Pass ID, which would have cost half as much, imposed fewer requirements and offered more federal grants. But the proposal died in the last session of Congress.

Twenty-four states are refusing to comply with the regulations, according to the National Conference of State Legislatures.

Sixteen of them -- including Arizona, Georgia, New Hampshire, South Carolina and Utah -- have passed laws prohibiting compliance with Real ID, most of them citing privacy and funding issues. The other eight, including Arkansas, Colorado, Illinois and Nevada, have passed resolutions opposing the law.

Homeland Security officials did not mention the open revolt by those states in its statement announcing the extension.

"Implementation of Real ID involves a significant financial investment, and, despite the receipt of substantial federal grant funds, a number of states are struggling to come up with the resources necessary to meet the full compliance deadline in these times of budget austerity," the department said. "Additionally, some states delayed investing in new technology and process changes because of uncertainty associated with congressional action on the Pass ID Act."

"Now that Pass ID seems unlikely to be enacted, DHS anticipates states will refocus on achieving compliance with the Real ID requirement," the department added.

House Republicans lashed out at Homeland Security for granting another delay. They pointed to last week's arrest in Texas of Khalid Aldawsari for allegedly trying to use a weapon of mass destruction as reason why further delay risks national security. Aldawsari was allegedly seeking multiple drivers' licenses to avoid detection.

"The timing for such a delay is worse than ever," Texas Rep. Lamar Smith, chairman of the House Judiciary Committee, said in a statement. "The administration should not prolong Real ID implementation. By doing so, they disregard the law of the land. Delaying Real ID unnecessarily places Americans' lives at risk and threatens national security."

"In light of the Texas terror plot, it's inconceivable that the Obama administration would further delay the implementation of Real ID and not address this glaring vulnerability for another 21 months," Rep. Darrell Issa, chairman of the House Oversight and Government Reform Committee, said in a statement.

"We have a situation where we know we can take meaningful action to make the American people safer, yet for some reason, the president wants to delay action. I can't for the life of me understand why."

But the National Governors Association welcomed the extension.

"Protecting the security and integrity of drivers' license and state identification cards is a top priority of the nation's governors' however Real ID presents significant operational and fiscal challenges to states,' the group said in a statement. "Governors have long said that Real ID, in its current form, is unworkable. That has not changed."

"Extending the compliance deadline allows states and the federal government more time to find solutions that work," the group added. "Arbitrary deadlines that only keep people from boarding an airplane do not make the impossible possible."