Boosted by moderate Republicans' concerns about John Bolton (search) as the potential face of America at the United Nations, Democratic senators are attempting to buy more time to persuade fence-sitters to join them in voting him down.

Sen. Barbara Boxer (search), D-Calif., said Friday she would try to place a hold on Bolton's nomination and request more information about President Bush's pick for U.S. ambassador to the United Nations.

"It is not fair to bring this nomination to the floor for debate and a vote until all the information has been delivered," Boxer said in an interview.

Boxer said Democrats want information on whether President Bush's choice for ambassador sought the names of U.S. officials whose communications were intercepted by U.S. intelligence. They also want details on the private business activities of a Bolton assistant, Mathew Friedman, and on Bolton's speeches on Syria.

The Foreign Relations Committee (search) voted 10-8 Thursday to send Bolton's nomination to the full Senate without an endorsement. Usually, Senate committees endorse the nominations they approve.

Boxer notified Sen. Joseph Biden (search), D-Del., who is leading the fight against Bolton, that she was putting a "hold" on the nomination. That means she will force numerous procedural votes before the Senate can even begin debating the nomination.

Asked to assess Bolton's chances of being confirmed, Boxer said: "I think we can definitely beat John Bolton because, I think, the American people are going to weigh in and make their views known."

She said she would halt the procedural delays when Democrats receive the requested information. But, she said, "all options are on the table, including a filibuster."

A filibuster is a parliamentary delay that can kill a nomination unless 60 of the 100 senators vote to move ahead.

Republicans have a 55-44 Senate majority, plus one Democratic-leaning independent. Democrats hope to gain support from enough Republicans to defeat the nomination, though that is expected to be difficult.

One of the 55 Republicans, George Voinovich of Ohio, kept the committee from recommending approval of Bolton and said he would vote against confirmation.

Even so, the White House assumed a positive stance on Bolton's chances.

"We believe there is a majority of the Senate that agrees with the president that John Bolton is exactly the person we need at the United Nations during this critical time of reform," spokesman Scott McClellan said.

At a minimum, in playing for delay, the Democrats are making the White House squirm while renewing accusations that Bolton was overly aggressive as the State Department's top arms-control official, pushing his views and trying to damage the careers of officials who disagreed with him.

State Department spokesman Richard Boucher told reporters Friday that his department has no plans to provide more documents to the Senate Foreign Relations Committee, regardless of threats from Democrats to hold up the Bolton vote.

"We don't want to turn this into a showdown between branches of government," Boucher said, but "providing all the internal communications, the e-mails or whatever, notes might go back and forth in the process of changing words and modifying language and working on a speech, to provide all of that stuff in public without a chilling effect on the kind of deliberations and organization that people have to do in here."

Asked why the State Department has the right to determine what the committee "needs to know," Boucher said, "because we have the materials. We know what's in the materials."

Boucher maintained that it's the agency's position that it has been "very responsive" to the committee and concluded that "we don't think anything further is required before a floor vote."

Biden, the leader of the fight against Bolton, suggested Bush "would be better served by bringing the nomination down."

"It does not appear that Mr. Bolton has the confidence of a majority of the members of the Senate," Biden said.

If Bolton survives the bruising Senate fight, he will take with him to New York the scorching criticism of Democratic senators, the doubts of Voinovich and criticism even from Sen. Richard Lugar, R-Ind., who is managing the nomination.

"His blunt style alienated some colleagues," Lugar acknowledged.

Sen. Russ Feingold, D-Wis., called Bolton "a loose cannon."

Voinovich's doubts helped delay the vote for more than three weeks. In an impassioned and conflicted statement that electrified the committee's 51/2-hour meeting, he questioned the impact on the United Nations of naming an ambassador "who himself has been accused of being arrogant, of not listening to his friends, of acting unilaterally and of bullying those who do not have ability to properly defend themselves."

"These are the very characteristics that we are trying to dispel," Voinovich said.

Lugar, taking a contrary tack, said if Bolton goes to the United Nations and helps achieve reform, the U.N. will gain in credibility, especially among the American people. "Secretary Bolton has become closely associated with the United States' efforts to reform the U.N.," the chairman said.

Bush, aware of Voinovich's reservations, telephoned him Wednesday, a day before the vote. McClellan said Friday he was the only senator the president called.

Voinovich, in laying out a case against Bolton, called the nominee "the poster-child of what someone in the diplomatic corps should not be."

Yet, Voinovich said Bolton should be commended for his achievements. The senator cited Bolton's work in countering anti-Semitism, on a treaty to reduce stockpiles of U.S. and Russian nuclear weapons, and on a U.S. program designed to curb the spread of weapons technology.

After weeks of deliberation by the committee, interviews with 29 past and present U.S. officials and examining thousands of pages of documents, "I have come to the conclusion that the United States can do better than John Bolton," he said in a low voice.

Then Voinovich hesitated, put his prepared statement aside, and changed course — enough to keep the nomination alive and possibly ensure its approval by the full Senate.

"Mr. Chairman," he said, "I am not so arrogant to think that I should impose my judgment and perspective of the U.S. position in the world community on the rest of my colleagues. We owe it to the president to give Mr. Bolton an up-or-down vote on the floor of the U.S. Senate."

The committee, he said, should move it along — but without a recommendation to approve Bolton. "Let the Senate work its will," he said.

FOX News' Teri Schultz and The Associated Press contributed to this report.