The White House Thursday demanded a vote to confirm President Barack Obama's pick for Pentagon chief this week and blasted Republicans for sending a bad signal to US allies by delaying his appointment.

As a political standoff escalated, a top Democrat told AFP that his party may not have the votes to drive through Hagel's nomination as defense secretary before the Senate goes into a week-long recess.

White House spokesman Joshua Earnest said the delay had jeopardized Hagel's planned appearance at a NATO ministerial meeting next week in Brussels, with NATO powers to discuss the pull-out from Afghanistan.

"It is difficult to explain to our allies exactly why that is happening. It also sends a signal to our men and women in uniform," Earnest said.

"We need our new defense secretary to be there," he said, branding the Republican procedural tactics "unconscionable."

Before allowing a vote, Republicans had demanded more information on Hagel's finances and on Obama's role in responding to an attack on the US consulate in Benghazi, Libya last year.

Senate Democratic majority leader Harry Reid responded by trying to force a vote on the nomination, but will need five Republicans to get to the 60 votes needed to overcome the blocking tactics.

Without such a filibuster, presidential nominations require a simple majority of senators in the 100-seat chamber -- a barrier Hagel is almost sure to surpass.

Reid accused Republicans of acting like children over Hagel, saying it was "shocking" they would do so while the United States was at war.

"The filibuster of senator Hagel's nomination is unprecedented," Reid said. "For the sake of our national security, it's time to put aside this political theater -- and that's what it is."

Carl Levin, chairman of the Senate Armed Services Committee, told AFP that it was unclear whether Hagel would get the 60 votes this week.

"We don't know ... you're never sure until the vote," said Levin.

Hagel's hopes of swift confirmation appear to rest with his one-time friend and colleague Senator John McCain, who eviscerated him in a confirmation hearing and has not yet made clear whether he would support a filibuster.

McCain's fellow Republican hawk Senator Lindsey Graham suggested that he would drop his delaying tactics only after the Senate returns from a week-long recess in the week of February 25.

Both men Thursday got a letter from the White House with new details of Obama's actions on the night of the attack by militants on the consulate in Benghazi, which killed four people, including US ambassador Chris Stevens.

It confirmed that then secretary of state Hillary Clinton had called Mohammed Megaryef, president of the Libyan national assembly, on the night of the Benghazi attack but Obama had not.

Graham had argued that the extra weight of a demand by the US president, at a time when the consulate was under siege, might have mobilized Libyan forces more quickly and saved some American lives.

According to the letter from White House counsel Kathryn Ruemmler, Obama spoke to Megaryef on the night after the attack.

The letter prompted Graham to say he might drop resistance to a confirmation vote after the Senate break, a move which would clear the path for Hagel.

But he added a qualifier, saying "unless there's some bombshells, unless he, (said) that the Israeli government is bloodsucking vampires or something like that, I got a feeling I'd be ok."

Hagel was picked to replace outgoing Pentagon chief Leon Panetta at a time of rising tension in Middle East hotspots, budget battles at home and after this week's rogue nuclear test by North Korea.

Panetta spent his last day at work on Thursday before returning to his home in California, though will formally retain the responsibilities of Defense Secretary until his successor is confirmed.

Several Republicans have taken issue with Hagel's public stances in recent years on Iran, nuclear weapons, Israel and the US troop surge in Iraq.

They have demanded financial compensation data and transcripts from speeches Hagel gave to foreign audiences, saying some records are missing.

Republicans force delay on US defense chief vote
Washington (AFP) Feb 13, 2013 - Republicans demanding answers from President Barack Obama's pick to head the Pentagon forced Senate leaders Wednesday to delay a vote, throwing Chuck Hagel's confirmation into doubt.

Senators James Inhofe and Lindsey Graham have expressed strong opposition to rushing the confirmation process, and after Hagel was narrowly approved by the Senate Armed Services Committee on Tuesday along strict party lines, the Republicans insisted they would try to block a vote in the full Senate.

"This is the first time in the history of our country that a presidential nominee for secretary of defense has been filibustered. What a shame," Senate Majority Leader Harry Reid said on the floor of the chamber.

To overcome the blocking tactic, Reid scheduled a vote for Friday to end debate on the Hagel nomination, but such a procedure requires a 60-vote threshold rather than the typical simple majority.

Democrats hold a 55-45 edge in the Senate. No Democrats are expected to vote against Hagel, a Vietnam War veteran and Republican former senator. However, just two Republicans have publicly stated their support.

It remained an open question whether there were another three Republicans willing to cross party lines and allow the nomination to get to the floor.

"I would hope we would have 60 votes," Democratic Senator Dianne Feinstein told AFP. "I have not heard that there are not, let me put it that way."

If confirmed, Hagel would replace outgoing Pentagon chief Leon Panetta at a time of rising tension in Middle East hotspots, in the budget battle at home and after this week's rogue nuclear test by North Korea.

Senate Democrats have warned that now is not the time to waffle over a crucial cabinet member who directs the US military, and the White House has called for expeditious action to fill the vital post.

Spokesman Jay Carney said the White House has "100 percent confidence" that there was "majority (support for Hagel) and then some."

"So we ask Congress -- the Senate -- to move quickly to confirm him as secretary of defense."

Inhofe sought to downplay his effort to block a vote, insisting there was "nothing unusual" about it.

"I'd vote tonight if we could just get the information that's been requested by the Republican members of the Armed Services Committee."

He and colleagues have taken issue with several comments and votes by Hagel in recent years about Iran, nuclear weapons, Israel and the US troop surge in Iraq.

They have demanded financial compensation data and transcripts from speeches Hagel gave to foreign audiences, saying some records are missing.

Armed Services Committee chairman Carl Levin said the demands went beyond the level traditionally asked of nominees.

But Graham said he would "take every opportunity" to block a Hagel vote in order to get the questions answered.

"I don't think I'm being unfair to the process by saying 'slow down,'" Graham told reporters.

"I remember very well what the Congress did when it came to Bush administration failures. We provided oversight," he said, recalling bruising congressional investigations of the past.

"If the shoe were on the other foot, and this was a Republican president, I'd guaran-damn-tee there'd be a lot of Democrats doing what I'm doing."

On Wednesday, moderate Republican Susan Collins came out in opposition of Hagel, but stressed she would not prevent a floor vote.

"I oppose senator Hagel's nomination, but I cannot join in a filibuster to block each senator's right to vote for or against him," she said.

Republican Marco Rubio however was supporting the delay.

"It's not the preferred route," he told AFP, but "there is more information that we need to learn."