WASHINGTON--The problem with the debate over our future course in Iraq is that the two sides are not even talking about the same things.

For supporters of the war, the primary issue is Iraq itself and what happens if we leave. For the war's opponents, the focus is on how the conflict in Iraq is sapping our energies, weakening our military, and diverting our attention from our other interests in the world.

The bottom line of the testimony this week from Gen. David Petraeus and Ambassador Ryan Crocker is that even after the surge, what gains have been made in Iraq are, as Petraeus put it, "fragile and reversible." For the administration's friends, this can only mean that we need to stay the course. President Bush endorsed that approach on Thursday, meaning that 140,000 or so troops will still be in Iraq when he leaves office.

But the administration's critics (and even some of its sympathizers) see the current policy as the equivalent of constructing a very expensive road, under hazardous conditions, even though those building it can't explain exactly where the road will lead. The road becomes an end in itself. The point is to keep building it in the hope that it will eventually arrive at some lovely destination.

Such a project can go on only for so long before someone points out the obvious, which is what Sen. Bob Corker, R-Tenn., did during the hearings: "I think people want a sense of what the end is going to look like."

Sen. John Kerry, D-Mass., said in an interview that after five years of war, the argument that "we've got to take time, we need a little more time" simply falls apart.

The administration and its supporters talk incessantly about winning but offer no strategy for victory, no definition of what it would look like, no concrete steps to get us there, and no real sense of where "there" is.

John McCain gamely declared that "success is within reach." But what success does he have in mind? He still holds to the old dream of "a peaceful, stable, prosperous democratic state." But how that can happen, or when, is anybody's guess.

A conflict between Sunnis and Shiites has been replaced by a conflict among Shiites--and there is no guarantee that the old Sunni-Shiite fights will not flare up again. Is that success? Iran has used our invasion to expand its influence in Iraq. Is that success?

Here is Petraeus' memorable and candid account of where we stand: "We haven't turned any corners, we haven't seen any lights at the end of the tunnel. The champagne bottle has been pushed to the back of the refrigerator." Tell me again: What does success look like?

Supporters of the war say its opponents are locked in the past, stuck on whether or not the war was a good idea in the first place. Whether the war was right or wrong, they say, it's time to move on and focus on the future.

This has it backward. It's the war's backers and architects, including the president, who are trapped in the past. They are so invested in the original decision to invade Iraq that they won't even consider whether the United States would be better off winding down this commitment, relieving our military of the war's enormous burdens, and redirecting our foreign policy.

Instead, they want to push on, hoping that something turns up. They resemble their own parody of liberal do-gooders insisting on continuing flawed and foolish programs no matter how obvious it becomes that their efforts are doing more harm than good.

If this year's election is to be about the future, the debate cannot be over whether or not the surge "worked." McCain will have to provide a more specific and realistic definition of success. He will need to be much clearer than he has been as to how it would be achieved and when. Above all, he needs to tell us why an indefinite occupation of Iraq is worth the price.

And it will fall to Barack Obama and Hillary Clinton to argue persuasively that ending our obsession with Iraq is in fact the first step toward restoring American power.

There was a certain pathos in Bush's speech on Thursday as he made the usual promises, the usual optimistic noises and the usual resolute sounds about a war he never expected to go this badly. Iraq has become everything for Bush. That is no reason why it should be everything for the rest of us.

By E.J. Dionne, Jr.