Senate Foreign Relations Committee Democrats said on Sunday their party likely will not be able to block John Bolton’s nomination as U.S. ambassador to the United Nations but want more information before agreeing to a vote.

The Senate returns this week from recess and again will face the contested nomination, which has twice been delayed by Democratic concerns about Bolton, the top U.S. diplomat for arms control they say has a record of abusive, erratic behavior that should disqualify him for the sensitive diplomatic job.

Asked if Democrats would have enough votes to sustain a filibuster, a procedural hurdle used to block action and thereby block the confirmation vote, Sen. Joseph Biden of Delaware, the top Democrat on the panel, said, “I’m going to be completely straight with you. I’m not at all certain we do.”

Sixty votes are needed to end debate and go to a final vote in the full Senate, which Republicans control 55-45.

“(Bush) will probably be able to win the vote somewhere between 45 and 47 votes against and he’ll think it’s a victory,” Biden told ABC’s “This Week” program.

“He is making a mistake, a serious mistake, not only institutionally, but for his own naked self interest,” he added.

The Senate put off Bolton’s vote after Democrats demanded the White House turn over information to shed light on if Bolton tried to tamper with intelligence assessments.

Sen. Chris Dodd, a Connecticut Democrat who is also on the panel, said Bolton likely would be confirmed if the administration provides the information the Senate wants.

“John Bolton would probably have the votes for confirmation if we can get beyond this request for additional information,” he said on CNN’s “Late Edition.” “… So I’m hopeful this week we can work out some compromise, vote on John Bolton.”

Democrats, joined by Ohio Republican Sen. George Voinovich, say Bolton is a hard-line conservative and a bully who tried to pressure intelligence officials into making their findings support his political views.

Biden said the White House had not handed over the information, a tactic Republicans accuse Democrats of using to stall the vote.

“The bottom line here is that the president can probably stiff us. The president can probably refuse to give us this information, which we’re completely entitled to as United States Senate and that is the reason why we’re not letting the vote go forward,” Biden said.