Under pressure to tighten the nation's security, the Bush administration and Congress labored Thursday to work out one sticking point on driver license standards but remained in a standoff over whether to allow airport screeners to unionize.

Bowing to the nation's governors and lawmakers, the Homeland Security Department was to issue new drivers' license rules Thursday giving states that need it an extension past the May 2008 deadline that Congress established two years ago for development of uniform standards.

But the administration remained staunchly opposed to a provision in both the House and Senate versions of a sweeping homeland security bill that would grant to homeland security workers the same collective bargaining and whistleblower rights enjoyed by most other federal employees.

The White House on Wednesday threatened to veto the massive bill over that one provision, because officials said that it would interfere with the kind of instant personnel decisions necessitated in an emergency situation. Enough Republicans have pledged to support the veto threat to sustain it, and Sen. Jim DeMint, R-S.C. is expected to introduce an amendment to strip that provision out of the bill.

"It is not in the interest of national security to offer collective bargaining rights in this instance," Sen. Craig Thomas, R-Wyo, said Thursday on the Senate floor.

Labor advocates call that a poor disguise for what they say is the real reason Republicans consider the provision a deal-killer: the party's longtime political opposition to labor rights.

A similar fight had been shaping up over looming federal regulations on drivers' license standards until Homeland Security Secretary Michael Chertoff told reporters Wednesday that the new rules he would announce Thursday would "comfort anxieties" of states that said the rules would be too expensive for them.

Governors, state legislators and members of Congress have railed against the new requirements. In January the Maine legislature overwhelmingly passed a resolution objecting to the law, and about a dozen other states also have balked at complying with it. Several are expected to pass laws or adopt resolutions declining to participate.

Chertoff promised flexibility but added, "There's got to be a disciplined approach to getting in compliance with the law and the extension has to be a reasonable length of time. It's not going to be an extension that takes you years into the future."

State officials have complained about the license requirements, which were in the 2005 REAL-ID Act, saying Congress didn't give them the money to convert their databases or enough time to develop driver's licenses that critics complain amount to a national ID card.

The law, passed in response to the terrorist attacks of Sept 11, 2001, requires all states to bring their driver's licenses under a national standard and to link their record-keeping systems.

"There's vividly in my mind a picture of the Florida driver's license Mohammed Atta carried that he used to get on an airplane to drive it into the World Trade Center," Chertoff said. "Shame on us if we don't do something to get a handle on what is the principal form of identification used in this country."

The administration is issuing the rules at the same time the Senate is considering ordering a two-year extension of the driver's license deadline as part of its debate over homeland security legislation.

Privacy advocates also have griped that a national database linking all the states' systems could promote identity theft.

The digital photo, and possibly digital fingerprint, encoded on the ID cards could make them more valuable to identity thieves because they would be more widely accepted, they claim.

"It's going to be a honey pot out there that's going to be irresistible to identify thieves," said Barry Steinhardt, a lawyer with the American Civil Liberties Union.