Senate Democrats said Tuesday they will try to prevent a final vote on John R. Bolton (search) to be ambassador to the United Nations unless the White House provides more information about his activities.

Sen. Christopher Dodd (search), D-Conn., said the Bush administration rejected a compromise he proposed last week to release some of the highly classified information.

Both Democrats and Republicans seemed to write off chances for any bipartisan deal to end the impasse on Bolton like the one that allowed votes on California judge Janice Rogers Brown (search) and two of President Bush's other long-stalled nominees for the federal bench.

"Our belief is that until that information is forthcoming, we should hold fast," Sen. Barack Obama, D-Ill., said after the weekly caucus luncheon of Senate Democrats.

Democrats contend Bolton and the judicial nominees all hold extreme views that make them unsuited to be neutral judges or, in Bolton's case, an effective diplomatic negotiator for the United States.

Dodd, after the caucus lunch, predicted Democrats could again deny Republicans the 60 votes they need to allow a final, up-or-down Senate vote on whether Bolton should be confirmed.

"I haven't done a nose count here, but based on the reaction in the room I think there's a strong feeling to continue the position," Dodd said. "This is now beyond Mr. Bolton. It's a question of whether or not the Senate has the right to certain information pertaining to a nominee."

Sen. Joseph Biden of Delaware, the top Democrat on the Senate Foreign Relations Committee and a leader of opposition to Bolton, had said the opposite Sunday. In an interview on ABC's "This Week," Biden said he doubted Democrats could continue to block a full Senate vote.

Before the Senate broke for a brief recess last month, Republicans had fallen four votes short of the 60 they needed to move Bolton forward. Senate Majority Leader Bill Frist, R-Tenn., has indicated a new vote is not likely this week.

Republicans hold a 55-44 majority in the Senate, with one independent, and the White House has predicted repeatedly that Bolton eventually will win confirmation.

Sen. John McCain, R-Ariz., said he doubts moderates of both parties can broker a deal like the one he helped negotiate on judges. There was more at stake on judges than the fate of a single nominee, McCain said. He supports Bolton's nomination, as did all but one Republican when Bolton's nomination was debated on the Senate floor last month.

Dodd, meanwhile, said National Intelligence Director John D. Negroponte (search) had personally rejected his compromise offer in a phone call late last week. Dodd had written to Negroponte to say the impasse over Bolton could be broken if the administration ruled out certain people as being among those mentioned in classified communications that Bolton reviewed when he was the State Department's arms control chief.

So far the administration has refused senators access to the names of the U.S. officials mentioned in 10 communications intercepted by the National Security Agency. That refusal was a key factor in the Senate's vote late last month to delay Bolton's confirmation.

Democrats have opposed Bolton's nomination in part because they say he shut out or retaliated against subordinates or intelligence analysts who disagreed with him. And they have questioned why he wanted the intercepted communications and whether he was targeting certain U.S. officials.

Democrats are also seeking internal State Department documents concerning Bolton's use of intelligence about Syria's weapons capabilities.