WASHINGTON — By delaying a confirmation vote on Chuck Hagel to be defense secretary, Senate Republicans have forced Leon Panetta to remain on the job he is eager to give up. But they’ve also given the White House an opportunity to cast the GOP as obstructing President Barack Obama’s assembly of a second-term national security team.

Senate Republicans temporarily blocked a Hagel confirmation vote on Thursday, insisting that the administration must first answer more questions about its handling of a terrorist attack last September on a U.S. diplomatic compound in Benghazi, Libya, that killed four Americans, including Ambassador Chris Stevens.

Jay Carney, the White House press secretary, called it “political posturing.”

“Just when you thought things couldn’t get worse, it got worse,” Senate Majority Leader Harry Reid, D-Nev., said after the GOP forced the delay.

The Senate action amounted to a parliamentary maneuver, with Democrats needing 60 votes for Hagel’s confirmation to move forward. It fell two votes short.

Still, Hagel is likely to win confirmation on a mostly party-line vote after the Senate returns from next week’s recess. Sen. Lamar Alexander, R-Tenn., said he expects many of his Republican colleagues to join him then to end the debate.

Alexander stopped short of predicting Hagel will be confirmed, but that is almost assured if he only needs a simple majority, and Democrats control the Senate by a 55-45 margin. Alexander called Thursday’s vote “unfortunate” and “unnecessary” because Hagel’s nomination came up on the Senate floor too quickly — just two days after it was approved by a divided Armed Services Committee.

The unprecedented stall tactic against a defense secretary nominee raised the rancor of frustrated Democrats, who immediately accused Republicans of threatening security and said they unnecessarily undercut U.S. credibility abroad.

“The world is too dangerous to have this period of uncertainty,” said Carl Levin, D-Mich., chairman of the Senate Armed Services Committee.

The nomination of John Brennan as CIA director was also delayed; the Senate Intelligence Committee pushed off a vote amid Republican demands that the White House turn over more details about drone strikes against terror suspects and about the Benghazi attack.

In contrast, the Senate swiftly confirmed John Kerry to succeed Hillary Rodham Clinton as secretary of state.

The Pentagon and CIA will continue under their current leadership, and Panetta will stay on as defense secretary until his successor is confirmed. At a Pentagon award ceremony for Clinton, Panetta said it was fitting to recognize her accomplishments as secretary of state on Valentine’s Day. And he said the second-best Valentine’s Day present would be for the Senate to confirm Hagel and allow Panetta and his wife to “get the hell out of town.” He said he’s got his belongings packed.

Reid said he hoped to proceed with an up-or-down vote on Feb. 26 and suggested that the Republicans’ maneuvers have left the Pentagon leaderless.

“What does that do to our standing in the world community?” he asked in remarks on the Senate floor.

Although he had made no secret of his hope to retire by now, Panetta will be back in the Pentagon next week.

His press secretary, George Little, said Panetta will fly to Brussels for a NATO meeting late next week where allies will consider the size and scope of a post-combat mission in Afghanistan. The U.S. is hoping allied nations will contribute troops and money for continued training of Afghan security forces, which are to be fully responsible for security by the end of 2014.

Obama himself suggested that Hagel’s absence from the Brussels meeting could hurt the war effort. He also criticized Republicans for blocking the Hagel nomination and forcing him to win 60 votes instead of the usual majority.

“It’s just unfortunate that this kind of politics intrudes at a time when I’m still presiding over a war in Afghanistan, and I need a secretary of defense who is coordinating with our allies to make sure that our troops are getting the kind of strategy and mission that they deserve,” the president said in an online chat sponsored by Google.

A veterans group that is backing Hagel’s nomination also lamented the delay.

“Our enemies look for any moment — however brief — of weakness,” said Jon Soltz, a Iraq War veteran and chairman of VoteVets.org.  

Republicans, led by Sens. Lindsey Graham of South Carolina and John McCain of Arizona, insisted the White House tell them more about how Obama handled the Benghazi crisis.

Seeking to break the logjam, the White House responded to a Feb. 12 letter from Graham, McCain and Sen. Kelly Ayotte, R-N.H., to Obama asking whether he spoke to any Libyan government official during the Sept. 11 assault about getting assistance. Republicans have sought to portray Obama as being out of touch during the attack.

Clinton called Libyan President Mohamed Magariaf on Obama’s behalf on Sept. 11 to coordinate additional support to protect Americans in Libya, White House counsel Kathryn Ruemmler wrote in the Feb. 14 response. Obama spoke to Magariaf on the evening of Sept. 12, she said.