All eight Democrats on the Senate Foreign Relations Committee are expected to oppose the nomination of John Bolton, who now serves as undersecretary of state for arms control and international security.
They are troubled by allegations that he mistreated subordinates and pressured analysts to reach certain conclusions on policy and intelligence matters.
Senator Chris Dodd, a Connecticut Democrat, discussed his concerns in a recent Meet the Press program on NBC:
"It seems to me that if you break down this wall, this wall that should exist between the policy setters and intelligence analysts, that that wall breaks down," Senator Dodd says. "That is not to suggest that you can argue with him, you can disagree with him, you can be blunt with him. But if you threaten their jobs and threaten to fire them, then I think the credibility of American intelligence suffers. And if you did that, as he did and it is not debatable whether or not he did - everyone will tell you he did - then I think he is disqualified, in my view."
Nearly all 10 Republicans on the committee have signaled they will support Mr. Bolton, even though some have expressed reservations about the nominee.
But one Republican, Senator George Voinovich of Ohio, says he has not yet made up his mind. His concerns prompted the committee last month to postpone the vote to allow for more time to consider the allegations against Mr. Bolton.
If Mr. Voinovich votes against Mr. Bolton, resulting in a tie vote in the committee, it would not be enough to kill the nomination, although it would make his confirmation by the full Senate more difficult.
Committee chairman Senator Richard Lugar of Indiana predicts all his Republican colleagues will back the nomination. Mr. Lugar says Mr. Bolton has the president's trust to reform the United Nations and should be confirmed.
Senator George Allen, a Virginia Republican, agreed. He also spoke on NBC's Meet the Press:
"John Bolton is one who will not suffer wastefulness, is one who is going to scrutinize the spending at the United Nations," Senator Allen says. "We as taxpayers in this country pay 439 million dollars a year, which is 22 percent of the United Nations budget. I want someone who is going to be a watchdog, to reform them, to make sure they do not have these scandals like the oil-for-food scandal that was propping up Saddam Hussein's regime."
At the White House Wednesday, spokesman Scott McClellan predicted Mr. Bolton would be voted out of committee and would be confirmed by the full Senate.