The chairman of the Senate Foreign Relations Committee urged President Bush on Wednesday to rule out unilateral military action against Iraq, saying it was the "single worst option" for dealing with Saddam Hussein.

Sen. Joseph Biden, D-Del., issued the appeal a day before Bush's speech on Iraq to the U.N. General Assembly. Bush is expected to ask the Security Council to compel Iraq to readmit U.N. weapons inspectors. It is not clear whether he will say the United States is prepared to use force against Iraq if the Iraqi president refuses to comply.

Biden, in remarks to the World Affairs Council of Philadelphia, said he will be "extremely disappointed" if Bush lays out a unilateralist approach in his U.N. speech that conveys the message, "`The world be damned, here we go.' That is not in our interest," Biden said.

He said Iraq has biological and chemical weapons and is trying to add nuclear capabilities. But he said he sees Saddam as someone who would give up his weapons in order to retain power and is not bent on destroying the world.

The tone of Biden's speech was milder than a letter he and fellow committee member Richard Lugar, R-Ind., sent Bush on Monday.

They asked Bush whether an attack on Iraq "would precipitate the every thing we are trying to prevent: the use of weapons of mass destruction against us or countries such as Israel."

Also Wednesday, Rep. Nick Rahall, D-W.Va., was heading for Iraq on Wednesday to inquire about the possibility of a U.S.-Iraqi negotiation to head off military action against that country.

Rahall and a group of other Americans, including former Sen. James Abourezk, plan to arrive in Baghdad Friday night and hope to have a meeting with Saddam.

"I hope their leadership will be open to a dialogue with our administration," Rahall said in an interview.

The Bush administration has shown no inclination to negotiate with Saddam. Its goal is disarmament, consistent with U.N. resolutions.

Rahall, who is of Lebanese descent, said he voted to support military action against Iraq 12 years ago but is worried that such action now could undermine the anti-terror coalition assembled by Bush.

Rahall said he and his colleagues plan to talk with Iraqi officials and ordinary citizens about the effect of 12 years of U.N. economic sanctions.

State Department officials did not try to discourage Rahall from taking the trip but cautioned that there may be risks to the personal security of the delegation.