(Adds details, quotes)
By Patricia Zengerle
WASHINGTON, Feb 13 (Reuters) - U.S. Senate Democrats filed a motion on Wednesday to end debate on the nomination of Chuck Hagel as President Barack Obama's new secretary of defense after Republicans refused to allow a vote, setting up a showdown vote by Friday.
Democrats are expected to muster the 60 votes needed in the 100-member chamber to clear a Republican procedural roadblock, clearing the way for a vote on his confirmation.
Once the roadblock is cleared, Hagel is expected to win the simple majority he needs to be confirmed.
Democrats control 55 seats in the Senate and none has come out against Hagel, a former Republican senator from Nebraska who has faced fierce opposition from members of his own party.
At least two of the 45 Republicans in the chamber have said they would vote for Hagel's confirmation, and several others, including Maine Senator Susan Collins on Wednesday, have said they would not support a procedural tactic to block or delay a vote even though they oppose Hagel's confirmation.
Hagel broke from his party by opposing former President George W. Bush's handling of the Iraq War, angering his former colleagues. Some Republicans also have raised questions about whether Hagel, 66, is sufficiently supportive of Israel, tough enough on Iran or capable of leading the Pentagon.
Hagel's performance during his confirmation hearing before the Armed Services Committee drew harsh criticism. Even some Democrats have said he appeared unprepared and at times hesitant in the face of aggressive questioning.
Harry Reid, the Senate Democratic leader, filed the motion to end debate after Republicans refused to give unanimous consent to allow a vote on Hagel's confirmation.
"It's the first time in the history of our country that a presidential nominee for secretary of defense has been filibustered," Reid said. "What a shame. But, that's the way it is."
BITTER PARTY DIVIDE
The Senate Armed Services Committee voted 14-11 along party lines on Tuesday to advance Hagel's nomination to succeed Leon Panetta as the civilian leader at the Pentagon.
During that meeting, some Hagel opponents, including James Inhofe, the top Republican on the committee, questioned Hagel's character, accusing him of being "cozy" with Iran or receiving compensation from foreign entities, drawing rebukes from Democrats and even other Republicans.
Others said Hagel had not been forthcoming and demanded more information about his finances and past speeches.
Levin rejected those concerns, saying some panel members were setting standards for Hagel that were far beyond what had been demanded of other nominees.
Hagel's nomination also got caught up in the continuing fight over the release of information about the September attack on U.S. facilities in Benghazi, Libya. Some Republicans threatened to block Hagel's confirmation if the administration would not release more information.
Republicans insisted they were not technically resorting to an unprecedented filibuster, saying they were just asking for more time to get more information.
"There's nothing unusual about this," Inhofe said on the Senate floor.
"I don't want to string this out. I have places to go other than hanging around here. I'd vote tonight if we could just get the information that has been requested by the Republican members of the Senate Armed Services Committee," he said.
The confirmation of another of Obama's national security nominees, John Brennan, his proposed CIA director, is also facing a potential delay amid jockeying between the White House and members of Congress.
Congressional sources said on Wednesday the Senate Intelligence Committee was likely to delay until the last week of February a vote on Brennan's confirmation. Democrats and Republicans are using the timing of the vote to pressure the White House to release sensitive papers.
(Additional reporting by Thomas Ferraro; Editing by Sandra Maler, Eric Beech and Lisa Shumaker)