The new Democratic majority in Congress is divided over how to assert its power in opposing President Bush’s plan to send more troops to Baghdad, as leaders explore ways to block financing for a military expansion without being accused of abandoning American forces already in Iraq.

While Democrats find themselves unusually united in their resistance to a troop increase, party leaders are locked in an internal debate over how far to go in objecting to the administration’s Iraq strategy. The White House has invited some Democrats to meet with Mr. Bush before he gives his Iraq speech on Wednesday, even as others have scoured the history books to find cases when Congress has reined in the commander in chief.

In the most aggressive of the new tactics, Senator Edward M. Kennedy, Democrat of Massachusetts, has said he will introduce legislation on Tuesday to require the president to gain new Congressional authority before sending more troops to Iraq. The bill is the first proposal in the Senate that would prohibit paying for an increase in American troops over their level on Jan. 1.

“Is there any American in this country who thinks the United States Senate would vote to support sending American troops into a civil war in Iraq today?” Mr. Kennedy said Monday in an interview. “Is there any American that believes this? I don’t think so, but that is what’s happening, and we have to do everything we can to insist on accountability.”

The Kennedy plan is intended to provide Democrats with a road map for how to proceed in Iraq. Mr. Kennedy, as he begins his 45th year in the Senate, recalled that Congress interceded during conflicts in Vietnam and Lebanon, and he said Democrats should not hesitate to do so in Iraq.

The new House speaker, Representative Nancy Pelosi of California, has similarly suggested that Democrats consider blocking financing for a troop increase, and the Senate majority leader, Harry Reid of Nevada, vowed Monday “to take a look at it.”

But the House majority leader, Representative Steny H. Hoyer of Maryland, has not endorsed the idea. Other Democrats, either looking ahead to a possible presidential candidacy or their own re-elections, have also distanced themselves from such a proposal, fearful of being cast as opposing the troops.

“I don’t think we should be pulling back any funds,” said Senator Amy Klobuchar, a Minnesota Democrat who was elected in November. She said she would oppose a proposal to block money for a troop increase.

The Democratic Party sailed to victory in midterm elections in the fall on a promise to change course in Iraq. Still, there is little consensus over how to proceed.

Some Democrats are urging an immediate withdrawal of troops and a drastic reduction in war spending. Others are calling for a gradual re-deployment of troops to move them out of Iraq. Still other Democrats are waiting for Mr. Bush to present his plan before criticizing it.

The expectations set by the elections, Democrats say, present a complicating challenge as they begin to govern.

Take, for example, Mr. Reid, who said on Dec. 17 that he would support a plan for a temporary increase in increase troops. Two weeks later, he announced his opposition, saying his change had nothing to do with other Democratic senators having spoken out against it, but rather with military officials having disagreed with a call for more troops.

Senator Russell D. Feingold, Democrat of Wisconsin, said he believed that his party lost the White House in 2004 because of Iraq. “My concern now is that too many Democrats are going to want to play it safe on this issue and not take the strong stand that American people demand,” he said Monday.

The pressure from war critics on the Democratic left has been particularly intense. “The bottom line is that they were elected on a mandate to get the nation out of the mess in Iraq,” said Eli Pariser, the executive director of MoveOn.org, a liberal political action committee.

Reverting to form, Democrats in Congress are cautiously trying to have it both ways so as to avoid having to take a stand on any of the issues that matter.

Faced with President Bush's own disastrous decision to go "double or nothing" on his losing Iraq War by adding another 20,000 or more troops to the front, House leader Nancy Pelosi and Senate leader Harry Reid chose to write a letter to the White House "urging" the president not to go that route.

The idea seems to be that if he goes ahead and sends the additional troops into the cauldron and things go from bad to worse, Pelosi and Reid will be able to say that they opposed the idea, while they will be immune from right-wing charges that they undermined the commander in chief, since they didn't do anything concrete to block his insane plan.

The truth is that Democrats could, if they had any principle and if they honored the wishes of the electorate, bring U.S. involvement in the Iraq War to a screeching halt. How? They could vote to cut off all funding for the Iraq War except for the costs of safely withdrawing all troops from the country. Nobody could accuse them, were they to do this, with putting American troops at risk. But they would have to face those who would accuse them of "cutting and running."

Democrats also have the votes to put an end to Bush's serial trashing of cherished civil liberties. Instead of grumbling about violations of the First, Fourth, Fifth and other Amendments, as Democrats have been doing so ineffectively now for five years, they could simply vote to revoke the 2001 Authorization for Use of Military Force, approved almost without objection by both houses of Congress back in September 2001 (resolutions are not subject to veto). It is that resolution which Bush and his mob attorneys in the White House and the "Justice" Department have been citing as justification for the president's assumption of dictatorial powers, such as the power to revoke habeas corpus rights of American citizens, the power to authorize torture and detention without trial, the power to kidnap and render people, the power to declare American citizens to be "unlawful combatants" devoid of citizenship rights, the power to invalidate duly passed acts of Congress, and the power to ignore federal laws like the Foreign Intelligence Surveillance Act. Revoke the 2001 AUMF and the president would have no grounds, fraudulent and unconstitutional as they in any case are, to claim that the nation is in a state of war and that he, as commander in chief, is no longer constrained by the Constitution.

We don't hear any calls in Congress to revoke the AUMF though, because that would require taking a concrete and resolute stand on principle in defense of the Constitution and the Bill of Rights, and taking the heat from right wing cranks who would accuse them of being "soft on terror." (Democrats aren't soft on terror; they are soft on the Constitution.)