President Bush's selection of Bolton last month has stirred controversy because of his expressions of disdain for the United Nations and the blunt criticism he has leveled at North Korea and other countries and arms control treaties.
Bolton, 56, has served in the past three Republican administrations and been one of his party's strongest conservative voices on foreign affairs issues. He is now the administration's arms control chief.
In a recent interview with The Associated Press, Secretary of State Condoleezza Rice defended Bolton by saying that "not everybody is given to subtlety and indirection." She said Bolton is a good negotiator and would be great in the U.N. environment.
Republicans control the Foreign Relations Committee by 10-8, but most if not all panel Democrats are expected to oppose the nomination. One of them, Sen. Bill Nelson, D-Fla., said Bolton has not been an effective arms negotiator and speaks to people in a condescending, inflammatory way.
"That's not the kind of representative of America that we want in the United Nations," Nelson said.
"The lobbying for and against Bolton has been intense, with serious talk of a filibuster if the nomination gets out of Committee on to the Senate floor," said CBS News Foreign Affairs Analyst Pamela Falk. "The good news is that it means that the nomination of the U.S. Ambassador to the U.N. matters, and that is more of a statement about the strong position of the U.S. at the U.N."
Committee Democrats also have circulated a portion of a 2-year-old Senate Intelligence Committee report questioning whether Bolton pressured a State Department intelligence analyst who tried to tone down language in a Bolton speech about Cuba's biological weapons capabilities.
On television talk shows Sunday, committee Democrats Christopher Dodd of Connecticut, Joe Biden of Delaware and Jay Rockefeller of West Virginia cited the alleged pressure and other alleged incidents as among reasons they will oppose Bolton's nomination.
Committee Chairman Richard Lugar, R-Ind., hopes for a vote on Bolton's nomination Thursday. A tie could keep the panel from recommending Senate approval.
"At the Committee Hearing on Monday, a lot will depend on how Senator Lincoln Chafee, the Republican swing vote, will view the testimony by State Department and intelligence officials," said Falk.
Chafee spokesman Stephen Hourahan said the Rhode Island senator was leaning toward supporting Bolton "unless something surprising shows up" at the hearing.