For Rick Santorum, the “big mo” in Arizona has probably come too late.

The former Pennsylvania senator has made little effort to woo the Grand Canyon State, where delegates are awarded on a winner-take-all basis. Instead, Santorum has focused on Michigan, where delegates are awarded proportionally and where his blue-collar message is likelier to resonate. But two polls (by CNN/Time and by the Democratic firm Public Policy Polling) released this week showed Santorum just a few points behind Romney in Arizona. (A third poll, however, by NBC/Marist, found Santorum trailing Romney by 16 points.) Santorum has also changed his tune, campaigning in the state the day before the debate.

“We’re not just here to debate,” Santorum said on the stump. “We’re here to win Arizona next Tuesday.”

State politicos are dubious that Santorum could pull off a surprise win, even if he is gaining significant traction in the state. In Arizona, a significant chunk of the electorate votes by mail — state Republican strategist Chuck Coughlin estimates that 70 to 80 percent of primary voters will do so this year — and those ballots can be returned as early as 30 days before the election. That means Santorum’s momentum will influence the decisions of only a significantly diminished number of voters.

“If you’d asked me that a week ago, I’d have said he had no chance,” says Arizona GOP strategist Brian Murray of Santorum’s odds of winning. Noting the PPP poll, however, Murray muses that “it sure seems like things are trending his way.”

“The big detriment that he faces is that in Arizona, probably 55 to 60 percent of the votes are going to be cast via absentee, which means Romney’s probably bagged a lot of votes,” he adds.

Maricopa County GOP chairman Rob Haney is similarly skeptical, questioning whether there’s enough time (and voters) left for Santorum’s momentum to change the outcome, although he thinks that Gingrich voters are likely switching over to Santorum now. But a win would require that “people have a big change of heart, and the vast majority of them in the last weekend send their ballot in for Santorum.”

Coughlin is doubtful that Santorum will carry the state, but notes that the Romney campaign has failed to aggressively court early voters.

“There’s an opportunity in any given campaign if you have early momentum to close the door on your opponent by virtue of a pretty simple calling-and-mailing campaign,” he observes. “When the ballot drops, that same day you get a piece of mail on that person, asking them for their vote, and then typically you do some phone calling after that, and you try to get them to return the ballot as quickly as possible.”

Such tactics, Coughlin comments, mean that campaigns can “bank an early lead.” He points out that “none of that’s happened in this cycle for Romney or anybody else,” and therefore “the door is still slightly open when it could have been closed.”

But if Romney failed to take full advantage of his early lead in the state, he still retains the Mormon vote — no small prize. Only about 6 percent of Arizona residents are Mormon, but they constitute an outsized share of Republican voters. “Santorum won’t beat Romney in Arizona — the monolithic nature of the Mormon vote will be too much for him to overcome,” says Arizona Republican operative Sean Noble, who estimates that the Mormons will make up a fifth of primary voters. Coughlin, who estimates that the percentage of Mormon voters ranges from 20 to 25 percent, says they will help Romney considerably: “That’s a significant advantage he has here.”

For Romney, who was expected to score an easy victory in Arizona, a close final vote count with Santorum could provoke another round of discussion about Romney’s long-term viability as a candidate. “I think it’s the same thing he’s had everywhere else,” says Coughlin. “I think it’s just that people are having a hard time connecting with the governor on a personal level.” Haney gives a different explanation, attributing Romney’s lack of traction to questions about his conservatism. “Arizona’s a conservative state and people are aware of what he’s been before and they’re not convinced that he’s conservative,” he says, alluding to Romney’s Massachusetts record.

“I think it will be close if he doesn’t win,” Haney says of Santorum. “If he does, it will be a huge upset. If he does come close, it will still be part of the momentum [showing] how far he’s come in such a short period of time.”

“In either case,” he adds of Tuesday’s outcome, “I think it’s bad news for Romney.”

— Katrina Trinko is an NRO reporter.