President Bush must explain why driving Iraq out of Kuwait is a vital U.S. interest, a leading senator says as Democrats urge the president to seek a broad consensus before launching a military offensive.

Congress needs to be involved in any decision to fight, several congressional Democrats said Sunday, several days after Bush announced plans to nearly double the 230,000 troops in the Persian Gulf to provide an "adequate offensive option.""The last thing we need is to have a war over there, a bloody war, and have American boys being sent and brought back in body bags and yet not have the American people behind them," said Senate Armed Services Chairman Sam Nunn, D-Ga. "We've gone that route one time. We don't need to do it again."

"It's not for the president by himself to decide whether or not to go to war," Sen. Daniel Patrick Moynihan, D-N.Y., said Monday on ABC's "Good Morning America." "He has to have the Congress with him, that is the law."

"If George Bush wants his presidency to die in the Arabian desert, he's going at it very steadily and as if it were a plan," Moynihan said.

Rep. Lee Hamilton, D-Ind., said Bush "ought to have the broadest possible achievable international consensus" before launching an offensive.

"The decision to go to war ought to be a shared responsibility, it ought not to be made by one person, even if that person is the president of the United States," Hamilton, a key House Foreign Relations Committee member, said on NBC-TV's "Meet the Press" program.

Senate Majority Leader George Mitchell, D-Maine, appearing on ABC-TV's "This Week With David Brinkley," said Congress must vote before America goes to war. And Senate Foreign Relations Chairman Claiborne Pell, D-R.I., said the United Nations "should have some input" before U.S. troops go into combat.

Nunn said Bush's new offensive posture was at sharp odds with the original objective of defending Saudi Arabia.

"It is something the military were not given to begin with and were not prepared for," Nunn said on the CBS-TV program "Face the Nation." "And I think the president has a real obligation here - perhaps he can do this, he should - to explain why liberating Kuwait is in our vital interest."

Sen. Richard G. Lugar, R-Ind., said Congress should vote on a declaration of war before any substantial military conflict with Iraq. And Vietnam-era Secretary of State Henry Kissinger said lawmakers should not be allowed to say they were kept ignorant as the nation became embroiled in war. Lawmakers were unanimous in saying they did not believe Bush had yet made a decision to go to war with Iraq over its Aug. 2 invasion of Kuwait.

Mitchell, reiterating recent statements, said "Congress and only Congress can commit the nation to war. The president has no legal authority."

He and House Armed Service Committee Chairman Les Aspin, D-Wis., said it was not time yet to call Congress into session for such a debate. They said it would only be "hypothetical" because Bush has not yet decided to launch combat operations in the gulf.

Pell, also appearing on "Meet the Press," said that unless U.S. lives were at stake, America should not launch a combat drive without congressional approval, "if not a declaration of war, at least a resolution of authorization."

Nunn renewed an earlier warning against American involvement in a ground war in the region.

"I think getting bogged down in a ground war there is the last thing we want and plays right into Saddam Hussein's hands and makes our logistics difficulties, which are already present, much more difficult," he said.

Lugar told a seminar in Fort Wayne, Ind., that lawmakers should debate a declaration of war against Iraq if the president comes to the conclusion that offensive force is necessary.

"If we are going to have this substantial conflict with Iraq and other nations, then I believe Congress should debate that and vote on a declaration of war," Lugar said at the Saturday seminar.