Donald TrumpDonald TrumpSanders laughs off Trump's third-party question Sanders: Clinton showing 'tinge of arrogance' Trump and Sanders whip up debate buzz MORE faces a major test Tuesday in Arizona’s presidential primary, the largest winner-take-all contest left in the Republican race.
If Trump can beat back a challenge from Ted CruzTed CruzFiorina returns to attack Clinton's 'lust for power' Trump clinches GOP nomination Eleven states sue Obama over transgender bathroom directive MORE, he will win all of the state’s 58 delegates and move closer to securing the nomination outright before the GOP convention in Cleveland in July.
Polls show Trump will enter Election Day as the favorite. But Republicans on the ground in the state say the contest could be decided by a razor-thin margin, and that Cruz is just as likely to finish on top.
“I think Cruz will pull the upset,” said Kurt Davis, a neutral GOP operative in the state and close confidante of Sen. John McCainJohn McCainOvernight Defense: Pentagon denies troops on Syrian front lines | Senators push for more Afghan visas McCain files B amendment to boost defense spending Senators push to authorize 4,000 more visas for Afghans MORE (R-Ariz.). “He’s the only candidate with any kind of organization out here and they have him positioned to spring the upset. They just have to deliver.”
There have been only two public surveys of Arizona released this month. Each found Trump with support in the 30 percent range, with leads of 12 and 14 points over Cruz.
“It’s significant but it’s not insurmountable,” said Tara Blanc, the co-director of the Merrill Poll, which conducted one of the surveys.
There hasn’t been any polling completed of Arizona since Marco RubioMarco RubioTrump encourages Rubio to reclaim Senate seat The Trail 2016: Interleague play Rubio: I'd speak on Trump's behalf at convention MORE dropped out of the race, and the overall samples of the state have been small so far.
Republicans expect many Arizona voters will make their decision late, as the state has seen little of the candidates so far.
That will change over the weekend, when Trump and Cruz make a furious late push in the state. Ohio Gov. John Kasich is concentrating all of his resources on neighboring Utah, where Republicans will caucus in a lower-stakes, proportional contest on the same day.
Trump, who has previously drawn thousands to rallies in Arizona, will return on Saturday for an event in the state’s most populous county.
Cruz, meanwhile, traveled Arizona to hold a press conference at the southern border. That evening he held a rally at a Christian college with former Texas Gov. Rick Perry — an active surrogate in Arizona — and former GOP presidential candidate Carly Fiorina and conservative media personality Glenn Beck.
The Cruz campaign has also gone on television in Arizona with an ad that highlights the murder of an Arizona citizen at the hands of an illegal immigrant.
The Texas senator will be looking to leverage an organizational advantage that has so far kept him running competitively with Trump.
While Trump has so far run up the score among early voters in several states, Cruz’s get-out-the-vote efforts have helped him close strong. He consistently outperforms the polls and has surprised political watchers by making a race out of contests where Trump entered with a healthy lead.
Veteran Arizona political operative Constantin Querard is leading Cruz’s efforts in the state. Querard made his name mobilizing grassroots conservatives and delivering surprise victories to insurgent candidates in the state legislature.
Cruz’s biggest advantage may be that Arizona is a closed primary.
Only registered Republicans can cast ballots in the Arizona primary, which will prevent Trump from receiving support from independents and Democrats.
Arizona is a rare state where registered independent voters outnumber registered Republicans and registered Democrats.
“Party registration has been dropping like a rock,” said Chris Herstam, who was chief-of-staff for former Gov. Fife Symington (R-Ariz.)
Thirty-seven percent of Arizonans are unaffiliated with either of the major parties, while 34 percent are registered as Republicans and 28 percent are registered as Democrats.
“That could tip the balance in favor of Cruz,” said state Rep. T. J. Shope (R-Ariz.).
Still, it might not be enough.
Trump has consistently racked up huge leads among early voters. It’s estimated that a quarter-of-a-million Republicans in Arizona have already cast their ballots while Trump has held a lead in the polls.
Furthermore, the anti-Trump contingent among early-voters may be diluted, as some will have already cast their ballots for Rubio, who only bowed out of the race on Tuesday.
“Those small number of votes spread between Rubio and Kasich may be enough to allow Trump to win again with only 35 or 40 percent of the vote,” Herstam said
Trump also has endorsements from the two of the most prominent border hawks in the nation — Maricopa County Sheriff Joe Arpaio and former Gov. Jan Brewer.
“For Trump, those endorsements are huge because of the issue set they’re associated with,” Davis said. “The issues that made Sheriff Joe and Gov. Brewer famous are the same issues that Trump is running on.”
In addition to the delegate haul, the winner in Arizona will grab momentum as the GOP race enters a dry spell.
Arizona’s primary is the last major contest until April 5, and the last winner-take-all until late April.