The Obama administration will abandon a Dec. 31 deadline for states to tighten security requirements for driver's licenses, Homeland Security Secretary Janet Napolitano announced Friday.

Delaying the requirement, which faces opposition from governors and Senate Republicans over how it should be implemented, jeopardizes an immigration and security measure adopted after the Sept. 11, 2001, terrorist attacks. But it also removes concerns that tens of thousands of holiday travelers could have been subjected to heightened airport security checks if they lacked the new licenses.