MARSHALLTOWN, Iowa — With four days left until the Iowa caucuses, Rick Santorum finally has become the flavor of the month in the volatile Republican presidential race here.

He has lagged in the bottom tier of public polling all year long. He’s someone who lost his race for a third term as the junior senator from Pennsylvania by an eye-popping 18 points back in 2006. And he’s talking more about abortion, marriage and Iran than the economy.

And yet, finally, Santorum has gotten his moment in the spotlight — and it’s at just the right time. There’s no telling now who will win the caucuses on Tuesday night.

Friday afternoon in Ames, where college students gathered at the local Buffalo Wild Wings to watch the hometown college football team compete in the Pinstripe Bowl, Santorum dropped by to shake hands and take advantage of the crowd in the full, loud bar.

He stopped along the way for several interviews — two with Fox News — and waved and smiled at reporters he hadn’t seen in ages but who had finally returned to cover the latest insurgent in the race.

And later, here in Marshalltown, he instructed his audience not to listen to pundits saying he doesn’t have a chance. “Your job is to make the tough call,” he told voters.

“Money didn’t really matter in this race,” he said, crowing about his late rise. “What mattered is talking to Iowans.” He added that no candidate can buy Iowa — a reference to Mitt Romney and Rick Perry, whose campaigns and allies have spent millions of dollars on Iowa’s airwaves of late. Still, the recent surge allowed Santorum to raise more money Thursday than he had in any single day previously in the campaign.

Friday morning, his emergence as a hot candidate was featured in a lengthy front-page article in the Los Angeles Times. He got the Wall Street Journal’s treatment the day before. And his potential to upend the caucuses was Friday morning’s top story on NBC’s “Today” show. If you haven’t figured it out yet, the media have decided that Santorum is the one with the so-called “big mo.”

It’s been a strange road: The winding course of the GOP primary has tended to follow the collective media narrative that develops (and re-develops) at each turn. Michele Bachmann would surge and then plummet, and she did. The same would happen to Herman Cain. The media projected Rick Perry’s rise and fall, and Newt Gingrich’s too. And it’s been the media that have been expecting a last-minute push by Santorum, and they got their wish — as they pulled it along.

The problem for Santorum, however, is that even though he shot up to third place in the state behind the statistically tied Ron Paul and Mitt Romney (according to a CNN poll out Wednesday afternoon), it’s not all breaking his way. Gingrich and Perry are still considered the two major candidates to the right of Romney — the ones who can take the fight to South Carolina as the conservative alternative, as they have the money and infrastructure.

And even in Iowa, they are not finished yet. Influential conservative radio host Simon Conway threw his support to Perry late Friday. And Steve Deace, another radio host who is a Christian conservative and who was influential in Mike Huckabee’s nine-point victory over Romney here in 2008, has backed the former House speaker.