Mitt Romney took some heat after saying in South Carolina last week that he would not negotiate with the Taliban in Afghanistan. Commentators such as my colleague David Ignatius pointed out that he was contradicting one of his top advisors, Mitchell Reiss, who has advocated talks. Others said he was ruling out the only possible route for ending the war.

So in NBC’s Florida GOP debate Monday night, Brian Williams offered Romney a chance to back off his position — or double down. “Governor, how do you end the war in Afghanistan without talking to the Taliban?” Williams asked.

Romney doubled down: “By beating them,” he replied.

If Romney survives the challenge from Newt Gingrich, that answer could set up an important general election debate with President Obama. One of the administration’s most aggressive and ambitious diplomatic initiatives involves trying to jumpstart negotiations with senior Taliban leaders in the Persian Gulf emirate of Qatar. Administration officials have said they are considering the transfer of five senior Taliban commanders from the Guantanamo Bay prison to Qatar as part of a possible Taliban move to open an office there.

Obama will argue that a political settlement is the only way to end the war, and that by opposing it Romney is dooming the United States to an endless commitment of troops there. The president’s plan is to cease all U.S. combat operations by the end of 2014, though negotiations are underway with the Afghan government about an American military commitment beyond that date.

Romney previewed his side of the argument to Williams. In addition to defeating the Taliban, he said, the U.S. goal should be to “transition to the Afghan military” in a way that allows it to “hold off the Taliban” on its own. Obama, Romney added, had made failure in Afghanistan more likely by setting a deadline for withdrawals, by speeding up a troop withdrawal this year so that it will be carried out by September, and by allowing a bad Afghan presidential election in 2009 that weakened and discredited the government of Afhgan President Hamid Karzai.

Despite Williams’s skeptical tone, Romney’s position is hardly out the mainstream. In fact, it closely tracks with the views of senior U.S. military commanders and some NATO and U.S. diplomats in Kabul — not to mention Karzai himself. Their assessment is that senior Taliban leaders are very unlikely ever to accept Karzai’s government, much less the Afghan constitution with its provisions for democracy and human rights. The generals also resisted Obama’s 2012 drawdown, which will be carried out before the November election — but also before the completion of this year’s “fighting season” on the ground.

Romney’s position could be undercut if Taliban leaders offer significant concessions as a result of the administration’s diplomatic efforts. But so far they appear unready to deliver anything very tangible in exchange for the opening of the Doha office and release of their leaders. U.S. officials are saying only that they hope to extract a statement renouncing international terrorism. The group has rejected the idea of negotiating with what it calls “the stooge Karzai administration,” as opposed to the United States. And it has not indicated any willingness to give up violence — though U.S. military operations in southern Afghanistan have greatly reduced its military clout.

A lot could change in Afghanistan between now and Labor Day. For now, however, whether or not to cut a deal with the Taliban — with all of its possible benefits and costs — looks like it could be a bright dividing line between Obama and his GOP challenger. When Williams invited Gingrich, Rick Santorum and Ron Paul to support the prospective negotiations, all remained silent.