WASHINGTON - Senate Democrats secured the backing of a significant number of Republicans in a crucial test vote Wednesday on a new U.S.-Russia arms-control treaty, President Obama's top foreign-policy priority.

The 66-32 vote to take up the treaty bolstered White House and senior Democrats' contention that they will have the two-thirds majority needed to ratify it before Congress adjourns for the holiday, even though a majority of Republicans prefer waiting until next year.

Nine Republicans, including Sen. John McCain of Arizona, Obama's 2008 presidential rival and a top lawmaker on national security issues, supported moving ahead on the treaty now.

Obama has said he is prepared to delay a planned holiday vacation until the treaty is completed, elevating the measure to year-end, must-do status along with the tax deal he cut with Republicans. Democrats are determined to push the treaty through the Senate in hopes of giving Obama a foreign-policy victory before the end of the year.

"We believe we should stay here as long as it takes to get this treaty ratified, and we are prepared to do so," said Foreign Relations Committee Chairman John Kerry (D., Mass.).

Still, several Republicans, led by Sen. Jon Kyl of Arizona, objected to considering the treaty in the waning days of Congress' lame-duck session, insisting the Senate should delay action until it has more time.

Sens. Lamar Alexander (R., Tenn.) and Saxby Chambliss (R., Ga.) said they could support the treaty but not under the current timetable. Alexander told reporters it was "reckless."

Speaking for the treaty before Democrats took their turn, Republican Sen. Richard G. Lugar of Indiana, who supports the treaty, said it "will enable American teams to return to Russia to collect data on the Russian arsenal and verify Russian compliance. These inspections greatly reduce the possibility that we will be surprised by Russian nuclear deployments or advancements."

Angry accusations marked the hours before the vote as Republicans threatened to force the treaty, signed in April, to be read aloud in the Senate, which would have delayed consideration. The White House called the GOP out on that idea, with press secretary Robert Gibbs assailing it as a "new low in putting political stunts ahead of our national security."

Gibbs singled out Sen. Jim DeMint (R., S.C.) for what he called delaying tactics.

Several Republicans had argued that the limited time available in the lame-duck session made it difficult to give the treaty the consideration it deserved.

Obama signed the treaty with Russian President Dmitry A. Medvedev in April. It would allow each country 1,550 strategic warheads, down from the current ceiling of 2,200.