The gap between public opinion and Washington reality has rarely been wider than on the issue of the Iraq War. A clear national mandate is being blocked – for now – by constraints that make sense only in the short-term calculus of politics in this capital city.

The public verdict on the war is plain. Large majorities have come to believe that it was a mistake to go in, and equally large majorities want to begin the process of getting out. That is what the polls say; it is what the mail to Capitol Hill says; and it is what the voters signaled when they put the Democrats back in control of Congress last November.

But it is not what will happen – at least now. The failure of the House last week to override President Bush’s veto of an Iraq spending bill that included a timetable for withdrawal makes that certain. The Democratic leadership already has signaled its readiness to drop the timetable, and further concessions are likely as negotiations continue with the White House.

The question that naturally arises is why the strongly expressed judgment of the people – responding to news of increasing American casualties in a seemingly intractable sectarian conflict – cannot be translated into action in Washington.

Part of the answer lies in the Constitution. It makes the president the commander in chief of the armed forces, the only elected official whose orders every general and every private must obey.

Congress shares the war-making power under the Constitution, but can exercise it only through its control of the money the president needs to finance any military operation.

In this moment, the commander in chief has a clear plan – to apply more military force in and around Baghdad in hopes of suppressing the sectarian violence and creating space for the Iraqi politicians to assemble a functioning government.

It is a high-risk policy with no guarantee of success. But it is a clear strategy.

The Democratic-controlled Congress, on the other hand, lacks agreement on any such plan. Most Democrats, at the moment, are unwilling to exercise their right to cut off funds for the war in Iraq, lest they be accused of abandoning the troops in the middle of the fight.

Lacking the will to do that, they are forced to an uncomfortable alternative. They are proposing to continue financing a war that most of them oppose, while placing conditions on the conduct of the war that the president says will reduce the chances of his strategy succeeding.

That claim, whatever its merits, places the Democrats on the defensive. It is not a comfortable position, but it is where they find themselves – for now.

But it is only for now. Come September, when Gen. David Petraeus, the commander in Iraq, says he will be able to judge whether the new tactics and the nearly 30,000 additional troops have turned the tide in the effort to reduce the carnage in Baghdad, different political forces will prevail.

If he is successful, and if the Iraqis begin to make the political accommodations needed to form a stable government, the president will be in a far better position to rally domestic support for the cause. If not, you can expect to see many congressional Republicans joining the Democrats in a demand for a “Plan B” that would likely lead to an early exit by a substantial portion of American troops.

One way or another, public opinion ultimately will be heeded on the war in Iraq. It is hard to imagine the Republicans going into the presidential election of 2008 with 150,000 American troops still taking heavy casualties in Iraq.

But if that should be the case, the likelihood would be that the Democrats would soon take over the White House – and their president would be the one to end the war.

Wars do end when the American people say they must. Dwight Eisenhower was elected president in 1952 with a promise to end the Korean War. Richard Nixon was elected president in 1968 with a promise to end the Vietnam War.

And if George Bush doesn’t do it, a Democrat will win in 2008 with a promise to end the war in Iraq.