On Afghanistan, where 100,000 American troops remain, the candidates have been all over the map, but have yet to engage seriously with one another on their positions. Mr. Romney offered no specifics on Afghanistan during his speech on Friday, just saying he would “order a full review of our transition to the Afghan military.”

Mr. Perry, perhaps the most opaque so far on foreign policy, said during the CNN/Tea Party debate that the United States should continue to have a “presence” in Afghanistan, but that it was time to start turning responsibility for the country over to the Afghans. Mr. Perry has not disclosed who is advising him on foreign affairs and has not given an address on the topic.

Jon M. Huntsman Jr., a former Utah governor, has called for winding down the war to focus on rebuilding at home, and Representative Ron Paul, representing a more isolationist strain of thinking, has called for a swift withdrawal.

But the substantive debate among them has been limited.

“This is unprecedented,” said Leslie H. Gelb, president emeritus of the Council on Foreign Relations. “Beyond the standard Israel posturing, they don’t say anything on the Middle East or the Arab Spring. And here the Afghan war is still an enormous open wound, an ongoing war, and you hear nothing of that.”

The economy’s troubles have dominated the campaign so far and are likely to continue to do so as long as unemployment remains high. Still, history has also shown that national security has a way of moving to the fore and in many cases dominating presidencies.

Mr. Huntsman will be delivering his own foreign policy speech on Monday at Southern New Hampshire University. Mr. Huntsman, a former ambassador to China who speaks Mandarin Chinese, entered the race trying to elevate national security issues. But so far, he said Thursday in an interview, few people have been listening.

“I have been surprised” at the low prominence of national security debate in the campaign so far, Mr. Huntsman said, “especially given the times in which we are living.” In an op-ed column for Politico on Friday, Mr. Huntsman took a punch at his competitors. “Unlike my fellow candidates, my view of America’s role in the world is shaped by hands-on experience gained during four stints overseas and serving in foreign policy positions for three presidents.”