On the eve of their big showdown with the president over the funding of the war in Iraq and their push for withdrawal, Democrats have acquired a certain swagger that the White House will find difficult to deal with, even if it plays its strong hand and vetoes the spending Iraq supplemental spending bill. Democrats are confident that they are on the right side of the public debate on the war, and they genuinely believe in what they are saying. They are not just right; they are feeling righteous. "We're not going to back down on what we think is right for the country," Senate Majority Leader Harry Reid promised reporters on Thursday.

And they have messengers to tell the story.

When Senator Amy Klobuchar of Minnesota talks about being in Baghdad and Fallujah with soldier from her state, she does not sound like she's working from talking points -- indeed, she never does. "They didn't complain about their equipment, they didn't complain about their tour extensions, they didn't complain about the conditions that they were operating in. And the only thing that they asked me to do was to call their moms when [I] got home to tell them that they were safe. These are brave soldiers, and they deserve the best. And I think the best thing that we can do for these soldiers is to get this policy right." How does the White House and the GOP go negative on American moms?

The Iraq war effort is so discredited in the minds of the American people that the Democratic margin of error in dealing with the president on this issue is huge; they have sufficient room for screwing up to make even the most timid among them feel safe in challenging the White House.

"In my state of Pennsylvania, people didn't elect me to come down here and to endorse a stay-the-course, the-president-is-always-right policy. They elected me to lead," thundered Senator Bob Casey Jr. on Thursday, in urging the president not to veto the supplemental. "I think it's about time that this president listened to the will of the American people." The Amen chorus on that sentiment continues to grow.

But for all the high-noon atmospherics of the supplemental showdown, it will likely turn out to be a little anti-climactic. The real gut-check moment of the season for Democrats will come when they have to vote on the Feingold-Reid proposal to end funding for the war beginning March 31 next year.

It is easy to stand up to a foe with an approval rating in the 30s who's under siege from every direction. In the fight over the supplemental, somebody will give, and it seems increasingly likely that that somebody will be the person who just extended the tours of duty in Iraq by 25 percent, who has to explain why the new strategy seems to be making the Green Zone more vulnerable, and whose attorney general will have to explain to the Senate why the administration was playing politics with U.S. attorneys while Americans were fighting and dying in Iraq.

"It's incredible, it is beyond comprehension," says Vermont's freshman senator, Bernie Sanders, "that this president would veto funds for the troops because Congress chose to acknowledge the will of the American people. Once again, this is a demonstration of a president way out of touch with reality."

The president may well veto the supplemental as promised, but on a second go-around he may choose to plead the following: Though an inflexible, out-of-control Democratic Congress, with some GOP help, is playing politics with the fighting men and women in Iraq by sending him bills with drawdown timetables, he will sign it because he does not want Washington politics to compromise the sacrifice of the brave men and women in harm's way.

But leaving the supplemental aside, another round in the fight over the war will be happening soon enough: a vote on some version of the Feingold-Reid proposal -- either as an amendment to other legislation or a stand-alone measure. Feingold, who was among the first people to call for a timetable for withdrawal in June 2005, is smart enough not to be confident about the bill's passage. But he has watched the ground shift on this issue, and all of it in his direction.

"The Democratic caucus did not hold together on a timeline at first, it was just me," Feingold told me Friday. "I think what you're seeing with this bill are the outlines of what is likely to happen. Maybe not the same words, not the exact language, but the general outline." The proposal says simply that the president will begin redeploying troops 120 days after the law is enacted and that -- with exceptions for anti-terrorist activities, force and infrastructure protection, and training Iraqis -- no money can be used to fund the continued deployment of troops in Iraq after March 31, 2008.

The envisioned funding deadline makes many Democrats very nervous. "That's going to be the big question," Feingold said. "How much resistance there will be from Democrats who are worried that they will be portrayed as not supporting the troops?" But he finds the near-unanimity Democrats achieved on the supplemental particularly encouraging. And, with the majority leader as co-sponsor, the chances of the bill coming to the floor are close to certain.

So, after facing down the president in April, sometime in May many Democrats may look in the mirror and see fearsome Russ Feingold staring back at them. "When Americans voted in November, they didn't just want us to oppose the surge. They wanted us to end the war," insists Bernie Sanders, who is now a co-sponsor of the Feingold-Reid proposal. "And that's what some of us intend to do."