Updated

A moderate Republican senator said Wednesday she'll oppose the confirmation of Chuck Hagel to become President Barack Obama's secretary of defense, while other GOP senators signaled they may delay a floor vote on the nomination unless the White House provides more information about the deadly attack on the U.S. diplomatic mission in Benghazi, Libya.

Sen. Susan Collins, R-Maine, had been viewed as a possible supporter of Hagel, but she said Wednesday that his views on the most critical threats facing the United States are "unsettling."

In a four-page statement, Collins said Hagel was unwilling to ask the European Union to designate Hezbollah a terrorist organization in 2006, and he has been hesitant to back the use of all non-military options, such as unilateral sanctions, to pressure Iran into ceasing its nuclear program.

As Collins voiced her opposition, Senate Majority Leader Harry Reid, D-Nev., set the stage on Wednesday for a full Senate vote on Hagel's nomination. Reid filed a motion to limit debate and force a vote, which is expected to be held on Friday. Democrats hold a 55-45 edge in the Senate and have the numbers to confirm Hagel on a majority vote, but would need the support of five Republicans to clear the way for an up-or-down vote on Hagel.

A bitterly divided Senate Armed Services Committee on Tuesday voted to approve Hagel by a 14-11 vote, with all the panel's Democrats backing him to succeed Defense Secretary Leon Panetta. The committee's Republicans were unified in their opposition to their onetime colleague, a former two-term Republican senator from Nebraska and twice-wounded Vietnam combat veteran.

"I am unable to support Senator Hagel to be the next secretary of defense because I do not believe his past positions, votes, and statements match the challenges of our time, and his presentations at his (confirmation) hearing did nothing to ease my doubts," Collins said. "I regret having to reach that conclusion given our personal relationship and my admiration for Senator Hagel's military service. But I have concluded that he is not well-suited for the tremendous challenges our country faces during this dangerous era in our history."

Collins said she would not join in a filibuster to block a final vote.

Sen. Lindsey Graham, R-S.C., said Wednesday that he would vote against ending debate on Hagel's nomination to be defense secretary because he wants more information on Obama's actions on the night of the Sept. 11 raid on the mission in Benghazi. Ambassador Chris Stevens and three other Americans died in the Sept. 11 raid.

Graham, Sen. John McCain, R-Ariz., and Sen. Kelly Ayotte, R-N.H., wrote to Obama on Tuesday and asked whether he spoke to any Libyan government official during the assault.

"There seems to not be much interest to hold this president accountable for a national security breakdown that led to the first ambassador being killed in the line of duty in over 30 years," Graham said. "No, the debate on Chuck Hagel is not over. It has not been serious. We don't have the information we need. And I'm going to fight the idea of jamming somebody through until we get answers about what the president did personally when it came to the Benghazi debacle."

McCain declined to say Wednesday whether he would try to filibuster or delay Hagel's confirmation if Obama did not provide an answer. "My position right now is I want an answer to the question," he said.

After the committee vote, McCain said he did not want a filibuster of Hagel's nomination. "We have not filibustered a Cabinet appointee in the past and I believe that we should move forward with his nomination, bring it to the floor and vote up or down," he said.

Sen. Carl Levin, D-Mich., the chairman of the Armed Services Committee, said he's confident the White House will supply the information and that Hagel will be confirmed.