"The key to turning (Anbar) around was the shift in allegiance by tribal sheiks. But the sheiks turned only after a prolonged offensive by American and Iraqi forces, starting in November, that put al-Qaeda groups on the run." -- The New York Times, July 8

WASHINGTON -- Finally, after four terribly long years, we know what works. Or what can work. A year ago, a confidential Marine intelligence report declared Anbar province (which comprises about a third of Iraq's territory) lost to al-Qaeda. Now, in what the Times' John Burns calls an "astonishing success," the tribal sheiks have joined our side and committed large numbers of fighters that, in concert with American and Iraqi forces, have largely driven out al-Qaeda and turned its former stronghold of Ramadi into one of most secure cities in Iraq.

It began with a U.S.-led offensive that killed or wounded more than 200 enemy fighters and captured 600. Most important was the follow-up. Not a retreat back to American bases, but the setting up of small posts within the population that, together with the Iraqi national and tribal forces, have brought relative stability to Anbar.

The same has started happening in many of the Sunni areas around Baghdad, including Diyala province -- just a year ago considered as lost as Anbar -- where, for example, the Sunni insurgent 1920 Revolution Brigades have turned against al-Qaeda and joined the fight on the side of U.S. and Iraqi government forces.

We don't yet know if this strategy will work in mixed Sunni-Shiite neighborhoods. Nor can we be certain that this cooperation between essentially Sunni tribal forces and an essentially Shiite central government can endure. But what cannot be said -- although it is now heard daily in Washington -- is that the surge, which is shorthand for Gen. David Petraeus' new counterinsurgency strategy, has failed. The tragedy is that, just as a working strategy has been found, some Republicans in the Senate have lost heart and want to pull the plug.

It is understandable that Sens. Lugar, Voinovich, Domenici, Snowe and Warner may no longer trust President Bush's judgment when he tells them to wait until Petraeus reports in September. What is not understandable is the vote of no confidence they are passing on Petraeus. These are the same senators who sent him back to Iraq by an 81-0 vote to institute his new counterinsurgency strategy.

A month ago, Petraeus was asked whether we could still win in Iraq. The general, who had recently attended two memorial services for soldiers lost under his command, replied that if he thought he could not succeed he would not be risking the life of a single soldier.

Just this week, Petraeus said that the one thing he needs more than anything else is time. To cut off Petraeus' plan just as it is beginning -- the last surge troops arrived only last month -- on the assumption that we cannot succeed is to declare Petraeus either deluded or dishonorable. Deluded in that, as the best-positioned American in Baghdad, he still believes we can succeed. Or dishonorable in pretending to believe in victory and sending soldiers to die in what he really knows is an already failed strategy.

That's the logic of the wobbly Republicans' position. But rather than lay it on Petraeus, they prefer to lay it on Prime Minister Nouri al-Maliki and point out his government's inability to meet the required political "benchmarks." As a longtime critic of the Maliki government, I agree that it has proved itself incapable of passing laws important for long-term national reconciliation.

But first comes the short term. And right now we have the chance to continue to isolate al-Qaeda and, province by province, deny it the Sunni sea in which it swims. A year ago, it appeared that the only way to win back the Sunnis and neutralize the extremists was with great national compacts about oil and power sharing. But Anbar has unexpectedly shown that even without these constitutional settlements, the insurgency can be neutralized and al-Qaeda defeated at the local and provincial level with a new and robust counterinsurgency strategy.

The costs are heartbreakingly high -- increased American casualties as the enemy is engaged and spectacular suicide bombings designed to terrify Iraqis and demoralize Americans. But the stakes are extremely high as well.

In the long run, agreements on oil, federalism and de-Baathification are crucial for stabilizing Iraq. But their absence at this moment is not a reason to give up in despair, now that we finally have a counterinsurgency strategy in place that is showing success against the one enemy that both critics and supporters of the war maintain must be fought everywhere and at all cost -- al-Qaeda.