For now…

WASHINGTON — Senate Republicans on Thursday blocked a vote to confirm former Senator Chuck Hagel as secretary of defense, arguing that Democrats were trying to rush a choice that they needed more time to consider.

In a 58-to-40 vote that broke down almost strictly along party lines, Mr. Hagel, a Republican, fell just short of the 60 votes needed to cut off debate and clear the way for final consideration of his nomination. Republicans said they intended to allow a vote on their former colleague when the Senate returns from a break in 10 days, but Democrats said the Republican position amounted to a historic filibuster of the nominee for a post that is usually filled with bipartisan support.

Democrats vowed to hold another vote when the Senate returns from recess. And all signs indicated that many Republicans who voted against Mr. Hagel on Thursday would not do so then.

“Republicans have made an unfortunate choice to ratchet up the level of obstruction in Washington,” said Senator Harry Reid of Nevada, the majority leader, who said that he planned to call Mr. Hagel and say: “I’m sorry for the president, I’m sorry for the country, and I’m sorry for you. But we’re not going to give up.”

All day, a tense standoff played out in the Capitol as one party tried to force the other into a more politically undesirable position. Republicans, aware that Democrats would not relish calling a vote that could result in an embarrassing setback for the president, had hoped to press Mr. Reid to back down and reschedule after the Senate returns from its recess.