One of President Obama's top foreign-policy goals suffered a potentially ruinous setback when the Senate's second-ranking Republican said the U.S. nuclear treaty with Russia should not be considered until next year.

The statement Tuesday by Sen. Jon Kyl (Ariz.) stunned the White House and Democrats, who scrambled to save the pact. It came just days after Obama declared that ratifying the treaty was his top foreign-policy priority for the lame-duck session of Congress.

The New Strategic Arms Reduction Treaty (New START) needs 67 votes to pass. Because of Democratic losses in the midterm elections, it would be harder to approve next year, requiring at least 14 Republican votes rather than nine now.

The administration will make a last-ditch effort Wednesday to appeal to Kyl, the Republicans' main negotiator, in a meeting including Vice President Biden, Secretary of State Hillary Rodham Clinton and Secretary of Defense Robert M. Gates, several officials said.

"Failure to pass the New START treaty this year would endanger our national security," Biden warned in a statement Tuesday.

Kyl's decision came despite an administration offer Friday to pour an extra $4.1 billion into modernization of the nation's nuclear complex. Because the treaty would reduce both sides' stockpiles of nuclear weapons, Republicans have insisted that the administration spend more money to ensure that existing U.S. weapons are well maintained.

Kyl's decision reflects a more assertive Republican stance following the midterm elections.

"The price [for getting the treaty] went up after the elections. Everyone should have known that," said Henry Sokolski, executive director of the Nonproliferation Policy Education Center.

The New START treaty is the centerpiece of Obama's "reset" of relations with Russia - a policy that the administration credits with producing critical cooperation from Moscow on Iran and Afghanistan.

If the treaty were to fail, Obama's ability to negotiate other treaties would be damaged, foreign diplomats say.

New START reduces each side's deployed, long-range weapons from 2,200 to 1,550. More critically in the eyes of U.S. military leaders, it allows each side to inspect the other's nuclear forces, to ensure there is no hidden buildup. Such inspections stopped when an earlier treaty expired last year.

"Without ratification of this treaty, we will have no Americans on the ground to inspect Russia's nuclear activities . . . [and] less cooperation between the two nations that account for 90 percent of the world's nuclear weapons," Biden said.