Updated

Leaders in both the House and Senate said they plan to vote by Thursday on resolutions giving President Bush the authority he wants to end the threat from Saddam Hussein, the Iraqi leader Bush says is a "homicidal dictator who is addicted to weapons of mass destruction."

"This is one of the most consequential questions we will deal with for years to come," said House International Relations Committee Chairman Henry Hyde, R-Ill. The House planned for 21 hours of debate, beginning Tuesday, on legislation authorizing the president to use military force, if necessary, against Iraq.

The Senate also opens formal debate Tuesday, and Majority Leader Tom Daschle, D-S.D., who has reservations about the White House-backed resolution, saying he hoped for a final vote Thursday.

On Monday evening, President Bush urged Congress to support him as he seeks to build an international coalition forcing Saddam to open up to inspections and disarmament. "Congress will also be sending a message to the dictator in Iraq that his only choice is full compliance, and the time remaining for that choice is limited," he said in a speech in Cincinnati.

"President Bush laid out the clear, compelling and overwhelming justification for action to remove the threat posed by Saddam Hussein's terror regime," said Rep. Tom DeLay of Texas, the House's No. 3 Republican.

But Rep. Dennis Kucinich, D-Ohio, a leading opponent of military action against Iraq, said Bush had "failed to make a case for a unilateral and pre-emptive strike on Iraq. War is simply a failure of diplomacy."

Earlier Monday, House Majority Leader Dick Armey, after weeks of fence-sitting, endorsed giving Bush the authority to go to war against Iraq, while Democratic lawmakers contended that launching the war without the international community's support would be a mistake.

Armey, R-Texas, said his decision came after "a careful, exhaustive review of the facts and evidence against Saddam Hussein," including numerous briefings by administration officials about the dangers posed by Iraq's weapons of mass destruction.

Armey, who is retiring at the end of this session, has in particular questioned the propriety of the United States launching a pre-emptive strike against Iraq. "America has never been an aggressor nation," he said.

But he said he now believes Iraq violated the terms of the cease-fire agreement after the Persian Gulf War a decade ago, and "I don't see this as pre-emptive at all."

The White House-backed resolution urges the United Nations to enforce strict new rules on inspecting and disarming Iraqi weapons but authorizes the president to use unilateral force against Iraq if that does not happen, is expected to pass convincingly.

Lawmakers will be given a chance to vote on more narrowly drawn alternatives that limit warmaking authority to removing weapons of mass destruction or withhold authority for unilateral action until after U.N. inspections prove futile.

Sen. John Edwards, D-N.C., who has stood with Bush in advocating action to defang Saddam, criticized what he called the administration's "gratuitous unilateralism" in a speech Monday to the Center for Strategic and International Studies.

"We seem determined to act alone for the sake of acting alone, which may be the easy way to achieve our short-term ends, but will never result in long-term security," the potential Democratic presidential candidate said in prepared remarks.

Sen. Edward Kennedy, D-Mass., who opposes the president's Iraq policies, said a preventive strike "flies in the face of international rules of acceptable behavior." It would deprive America "of the moral legitimacy necessary to promote our values abroad," he said in a Senate speech.

Sen. Joseph Lieberman, D-Conn., speaking before the Woodrow Wilson International Center for Scholars, said a key test of America's role as an international leader is how it responds to the post-Saddam period.

"If, in the aftermath, we leave the Iraqi people to fend for themselves in chaos and squalor, without more freedom or opportunity, we will end up hindering, not advancing, the wider war against terrorism and slowing, not speeding, the world's march toward democracy the rule of law," he said.