Three days before the Republican presidential primary in Ohio, Mitt Romney was campaigning in Dayton when a woman stood up to ask a question that pointed to one of the most important missing debates of Campaign 2012, and to a widening division in the GOP over a critical foreign policy issue.

Vicki Chura said her daughter was on her second tour in Afghanistan with the 82nd Airborne Division. She said her daughter was increasingly frustrated by the lack of clarity of the U.S. mission there and desperately wanted to come home. What would Romney do as president to expedite the withdrawal of U.S. forces?

The economy is and probably will continue to be the dominant issue in the campaign, but the shooting rampage Sunday, allegedly by a U.S. soldier, that killed 16 Afghan civilians could push the Afghan war into the political debate.

The killings may or may not be a shock to the political system. At a minimum, they are likely to raise uncomfortable questions, particularly for President Obama, the architect of the current policy, but also for the Republican candidates. Even for those out of power, Afghanistan provides no easy answers.

Romney’s response to Chura’s question underscored why. He began by criticizing the president. He said that Obama has not clearly defined the U.S. mission to the American people, and that a president should report regularly on the goals and progress of any such mission.

Romney described the U.S. objective as one of building an Afghan security force capable of protecting the country’s sovereignty — which is not that different from Obama’s stance. Hoping to show empathy with his questioner, he said he wants U.S. troops to come home “as soon as humanly possible.” But he offered a big, broad caveat: They can withdraw, he said, “as soon as that mission is complete.”

Chura’s question underscored the growing public weariness at home about the war. The latest Washington Post-ABC News poll showed that more than half the country wants U.S. forces withdrawn even before they can train the Afghan army to handle security on its own. The conflict has not become another Iraq war in terms of public division and emotion, but beneath the surface is a clearly growing pessimism.

As the past few days have shown, Republicans face a debate within the party over what to do about a conflict whose objectives are so difficult to define and whose costs have been enormous. Republican dissent over staying the course in Afghanistan is not pervasive, but there is hardly unanimity.

On Sunday, former House speaker Newt Gingrich (Ga.) said the mission “may not be doable” and suggested that military force may not be able to accomplish the goals set by two administrations.

Among other candidates, Rep. Ron Paul (Tex.), an opponent of the U.S. intervention, has long called for winding down the war. Before quitting the race, former Utah governor Jon Huntsman Jr. called for a speedy end to the conflict and said the resources being spent on it should be used to rebuild the U.S. economy.

Former Mississippi governor Haley Barbour raised doubts about the war when he was considering a 2012 candidacy. “What is our mission?” he asked last March. He said the United States should not try to turn Afghanistan into “an Ireland or an Italy” or some other Western democracy.

These are questions first for the president, because the Afghan war is his now. As a candidate in 2008, he described Afghanistan as the central front in the fight against terrorism. During his first year in office, he approved a major increase in troop strength. With that troop surge, he took possession of a conflict started by President George W. Bush after the attacks of Sept. 11, 2001.

But Obama was also always mindful of the opposition to escalation within his own party, as well as to concerns from some of his advisers that Afghanistan could become another quagmire like Vietnam. So he sought to set limits on the mission in terms of time and resources, establishing deadlines for starting to bring troops home. He made clear to the military and, he hoped, to the public, that the United States would not stay indefinitely.

Afghanistan will not be among the achievements Obama highlights during his reelection campaign. His supporters will cite the killing of Osama bin Laden as a bold decision that shows his toughness as commander in chief. He will point to the end of the Iraq war as a promise kept from his 2008 campaign.

Given the state of things in Afghanistan, the country could be one of his vulnerabilities. But will Republicans have a consistent and coherent line of criticism of the president’s Afghan policy? The coming weeks may answer that question.

Former senator Rick Santorum (Pa.) highlighted one view Sunday while campaigning in Mississippi by saying that the president is making it “very, very difficult” to win the war because he had signaled when U.S. forces would leave. Santorum said that U.S. policy is unraveling because Obama has given the enemy hope that American troops will be out sooner rather than later.

He said Monday on NBC’s “Today” show that the United States should reassess and either make a full commitment to the war — something he said Obama has not done — or speed up the NATO-established timetable that calls for the handoff to Afghans to be completed in 2014.

Romney has tried to calm those who want U.S. forces out quickly, saying he does, too. But he has criticized Obama’s timetable for withdrawing the surge troops that were sent at the beginning of the year, and has vowed that he would listen to his military commanders, saying the president has not done that. He has said that Obama has not clearly articulated the goals of the mission, but Romney has not done so with any particular clarity himself.

Until now, the Republican candidates have been free to criticize the president when given the opportunity, but they otherwise keep Afghanistan in the background. The killings Sunday, which come at a time of deteriorating relations between the United States and Afghanistan, could force Obama and those who want to replace him to give the public a fuller explanation of what constitutes success, and the costs of achieving it.

For previous columns by Dan Balz, go to