DESPITE THEIR dramatic debate over whether the invasion of Iraq was a necessity or a mistake, President Bush and Sen. John F. Kerry essentially agree on what U.S. goals and strategy there should be in the coming year or two. That is less of a contradiction than it might seem: Regardless of whether the war was right, the situation it produced offers few if any responsible options other than those endorsed by both candidates. After a long series of mistakes and reverses on the ground, the Bush administration is now focused on creating a representative Iraqi government through elections, supporting it with a quick infusion of reconstruction funds, and training enough military and security forces to defend it from Baathist insurgents, Islamic extremists and foreign terrorists. Mr. Kerry promises to pursue the same objectives, only more competently, and to work harder in getting other nations to help. One alternative to this approach, a more extensive, U.S.-controlled nation-building process, already failed under the occupation administration of L. Paul Bremer. Another, the early withdrawal of U.S. troops, could lead to civil war in Iraq and a surge of extremism across the region.

The candidates' apparent agreement might seem to take the most critical question about Iraq off the table, leaving voters to judge Mr. Kerry and Mr. Bush on the basis of their dispute over the initiation of the war. In fact, it's not so easy. It seems to us the most important question of this election may be which of the two candidates is more likely to succeed in achieving the goals they have commonly embraced. Neither candidate entirely earns our confidence; both provoke troubling questions about their commitment or capacity to win.

Mr. Bush has been stronger in promising to stick with the mission in Iraq until the country is secure and "on the path to democracy." Although he ordered an ill-advised retreat from the insurgent-held stronghold of Fallujah last spring, the president appears determined to fight the terrorists and insurgents. Success in Iraq doesn't seem possible unless U.S. forces are prepared to destroy the enemy's bases and restore the government's authority across the country.

It's still not clear, however, that the Bush administration is willing or able to execute the nation-building that must accompany the military strategy. The president seems to have altered his previous opposition to such missions, but Defense Secretary Donald H. Rumsfeld and other senior officials remain openly skeptical. Mr. Rumsfeld already has begun speaking of replacing U.S. forces with Iraqi troops and hinting that the opportunity for Iraqis to establish new institutions with American help should be limited. There is also the record of the past 18 months to consider. Mr. Bush has consistently bungled the job of reconstruction, in part because of his unwillingness to commit enough troops to ensure security and in part because of a failure to listen to or fully involve leaders and experts from outside the Pentagon in the effort, ranging from the United Nations and the World Bank to Iraqis themselves. Could Mr. Bush now be counted on to mount a more effective program of institution-building and to stick with it for years? We have our doubts.

Mr. Kerry and the Democratic foreign policy veterans around him have been more supportive of nation-building, at least in other parts of the world. Though it's unlikely that fresh European troops will pour into Iraq under any circumstances, a Kerry administration might do better at recruiting international aid and expertise for reconstruction and at applying America's own resources to the job. But will Mr. Kerry be prepared to see through the battle against the insurgents and terrorists? He says he wants to "win," but he hasn't always been clear about what he means by that, and Mr. Kerry's insistence that Iraq was "the wrong war" tends to undercut what he and his advisers say is his commitment to "win the peace." Would Mr. Kerry persist in this mission even if fighting and American casualties continue well into his term? There is no way to know for sure.

How, then, to choose on Iraq? Some voters may reasonably conclude that Mr. Bush is more likely to stick to the essential mission of ensuring that Iraq becomes a victory and not a defeat in the war with Islamic extremists and terrorists. For others, Mr. Kerry may seem better matched to the formidable reconstruction job still to be done. The Bush administration's record of failure on the ground argues for a change in management. The question not entirely answered by Mr. Kerry's campaign is whether he would be as determined to see the mission through.

This is one in a series of editorials comparing the records and programs of the presidential candidates on important issues. Others can be found at