A new survey shows Rick Santorum is within the range of a statistical dead heat of Mitt Romney with just a week to go to Arizona's presidential primary.
And how they perform in Wednesday's debate in Mesa could swing it either way.
Public Policy Polling actually finds that Santorum actually is better liked among the 412 likely Arizona Republican primary voters between Friday and Sunday. But when asked who they actually would vote for, 36 percent chose Romney versus 33 percent for Santorum.
That's well within the survey's 4.8 percent margin of error.
Dustin Ingalls, the polls's assistant director, said part of Romney's edge could be attributable to questions on the minds of GOP faithful of who is in a better position to take on Barack Obama in November.
Newt Gingrich, who was briefly a strong challenger to Romney, was far back at 16 percent, with Ron Paul tallying the support of just 9 percent. And, at this point, only 7 percent of those questioned said they either wanted someone else or are not sure who they will cast their ballot for this coming Tuesday.
Ingalls said that leaves a lot riding on the debate.
"I think Santorum needs to basically convince voters that he can be elected, that he is the sort of satisfying conservative candidate they're looking for who can beat Romney and beat the president,'' he said. The goal for Romney, as the presumed front runner, is different.
"Romney needs to close the deal in the sense that he needs to knock Santorum down a peg,'' Ingalls said. And he said there's "still room to shift'' in the next week to change the outcome.
Less clear is how a last-minute endorsement might provide the necessary margin of victory in the winner-take-all-delegates primary.
Ingalls said he thinks these will matter only on the margins.
"They generally don't make that big a difference,'' he said. Ingalls pointed out, for example, that Romney lost South Carolina to Gingrich despite the endorsement of Gov. Nikki Haley.
"There are some voters that sort of elite endorsement can be a cue to,'' Ingalls said.
But he pointed out that just 25 percent of Republicans said their choice would be influenced by whoever Gov. Jan Brewer ends up endorsing. Brewer has kept her choices to herself, saying she will not decide until she hears from the candidates themselves on Wednesday.
Conversely, 21 percent said Brewer's choice would make them want to support someone else -- with the majority saying whatever the governor thinks makes no difference to them.
The views of Sen. John McCain elicited a similar response, with more than half saying they don't care. But fully 30 percent say McCain's endorsement of Romney makes them less likely to want to vote the same way.
The Republicans questioned are a bit more interested in what Maricopa County Sheriff Joe Arpaio has to say. Arpaio, who had endorsed Rick Perry early on, has been silent since the Texas governor dropped out of the race.
But even here, 44 percent say they will make up their own minds regardless of Arpaio's stance.
Broken down by segments of the GOP electorate, the poll finds Santorum with an 18-point lead over Romney among those who describe themselves as Evangelicals and up 13 points with self-described "very conservative'' voters.
Romney, however, has a 14 point edge with "somewhat conservative'' voters and a 17-point spread among those who say they are moderates. He also polls better than Santorum among seniors, Hispanics and women.