The season now ending with school bells and the return of Congress was supposed to be the "Iraq Summer." A coalition of antiwar groups promised 10 weeks of phone banks, billboards, petitions and protests targeted at 40 Republican members of Congress who support the war. "It's going to be like laying asphalt in August -- hot," boasted one organizer.

By this standard, August has been remarkably mild. It brings to mind a couplet by the poet Richard Wilbur: "What is the opposite of riot? It's lots of people keeping quiet."

During their summer vacation, Americans discovered that Gen. David Petraeus doesn't take one. And his energy and urgency have shifted the Iraq debate in some fundamental ways.

A few months ago, it was the received wisdom that Iraq was in the midst of a rapidly escalating civil war. That claim is no longer plausible.

While the level of violence is still unacceptably high, the surge has disrupted the cycle of escalation and proved that progress is possible. Lt. Gen. Ray Odierno's briefing this month was an antidote to pessimism. "Total attacks," he said, "are at their lowest levels since August of 2006." Some of the most violent and lawless regions of Iraq, such as Anbar and Diyala, have been stabilized with the cooperation of local Sunni leaders who have turned against al-Qaeda thuggery. Insurgents are being pushed out of population centers and then targeted in further operations. Sectarian murders in Baghdad have gone down by more than 50 percent in a few months, reaching their lowest levels since the Samarra mosque bombing. And new sectarian provocations -- such as the al-Qaeda bombings in Nineveh -- have not resulted in the usual spiral of revenge murders.

With the surge fully in place only as of last month, the suddenness of these results is startling. Skeptical military experts have returned from Iraq with praise for the Petraeus strategy. And supporters of the war have been left to wonder: What if these approaches had been employed a year earlier?

As the summer began, it seemed that Republicans in Congress were on the verge of mass defections over the president's conduct of the war and ready to embrace Democratic timetables for withdrawal. While Sen. John Warner's recent call for symbolic troop reductions by Christmas didn't help the administration's case, it is now mainly Democrats who are recalibrating their message.

Sens. Hillary Clinton and Barack Obama have been quick to praise the accomplishments of American troops in the surge. And one Democratic House member, Washington's Brian Baird, has gone further since returning from an Iraq visit. While gains are "still precarious," the "situation on the ground in Iraq is improving in multiple and important ways," he said. "I do not know the details of what the September report will contain, but I trust and respect Gen. David Petraeus and U.S. Ambassador Ryan Crocker. I have seen firsthand the progress they have made, and I firmly believe we must give them the time and resources they need to succeed."

Four months ago, Senate Majority Leader Harry Reid could confidently declare: "This war is lost." Now that is an open question. A recent Zogby poll found that a majority of Americans do not believe the war is lost. And this makes Democratic policies based on the assumption of hopelessness -- rigid timetables and funding cuts -- strategically irresponsible and politically risky. If defeat is inevitable, it makes sense to cut our losses. If defeat is only possible, preemptively ensuring it would confirm a long-standing Democratic image of weakness.

None of these shifts over the summer means that victory in Iraq is near, or even easily definable. Many political benchmarks remain unmet by the Iraqi government. But undeniable progress on the security front has some practical implications. Even if Democrats press a legislative timetable for withdrawal, it is unlikely that they will get the support of 17 Republicans in the Senate to override a presidential veto. The confrontation with Congress may be over by October. As the military has already stated, troop reductions will begin sometime early next year because the Army can't sustain the surge indefinitely. But the president will have gotten an extended period of intensified military activity before his term ends. And unless conditions deteriorate unpredictably, the next president may inherit a more manageable situation -- allowing him or her to make deliberate troop reductions as Iraqi capabilities increase, without turning parts of the country back over to extremists.

Much, of course, depends on the Iraqis themselves, because liberty is ultimately won, not given. But the summer, at least, has brought rumors of hope.