In the most important debate on the Iraq war since it began, the Senate was trying to craft a nonbinding resolution this week that objects to President Bush's plan to send 21,500 more troops into battle. Some critics want a far tougher approach, while the White House argues that any expression of doubt will embolden our enemies and hurt our troops.

As usual, both extremes are wrong. The challenge is to thread the needle between them so those who object to the escalation can make the point without micromanaging tactics or putting our troops in greater danger. Most important, the resolution with the best chance of passing so far will not call for a withdrawal or cut off funds.

That's the right approach. It is the role of the Congress to be a check-and-balance on the president, and it is perverse to claim that role should diminish because the stakes are high. It is precisely because the stakes are high that Congress must have a voice while also recognizing the president's authority as commander in chief and the practical effects on our soldiers.

The danger is that emotions over the prolonged slog, mixed with partisan politics, could turn the debate into a free-for-all that leads only to deeper divisions.

Yet for those of us who think Bush's troop plan is a major mistake, that risk is worth taking. The president's bungling has cost him the benefit of the doubt and his troop surge doesn't pass the logic test. He says everything depends on the Iraqi government while insisting more troops are needed to give it "breathing space." But even the latest national intelligence report argues that the growing mayhem will only get worse until Iraqi leaders stop it. Why, then, should we send more troops to die when they are not the solution?

We shouldn't, which is what the public says by a wide margin. Even those who scoff at public opinion — Vice President Cheney said the Senate "won't stop us" — should realize you can't fight a war without public support. At least in a real democracy.

The only question now is whether different degrees of unhappiness can be forged into a Senate consensus. Thanks to rules that require 60 votes to break a filibuster, the battle comes down to a scrum among Republicans, who suddenly seem as divided as Democrats.

So far, as many as 12 Republicans, out of 49, could join a solid majority of Democrats in backing a sensible, middle-of-the-road approach. The language is largely the work of Sen. John Warner, R-Va., who has emerged as the Senate's most important voice. As a secretary of the Navy during the Vietnam War, he is hardly a dove. And as head of the Armed Services Committee before the Democrats captured the Senate, he was a reliable supporter of Bush's policies.

But Warner came to doubt our approach and, after an October trip to Iraq, said we were moving "sideways." That was a turning point and, as a hawkish member of the president's party, he has the authority and respect to lead the charge for a course change. His resolution objects to additional troops while saying Congress should not reduce funding for those already there.

Hopefully, that approach will win large bipartisan support and get Bush's attention. If it passes and he ignores it, as Cheney threatened, the president may find himself fighting Congress as well as terrorists and an Iraqi civil war.

Michael Goodwin is a Pulitzer Prize-winning columnist for the New York Daily News.