Gov. Ron DeSantis faces the first — and possibly last — major test of his presidential campaign on Monday when Iowa Republicans gather amid subzero temperatures to pick their nominee.

DeSantis needs to finish ahead of former South Carolina Gov. Nikki Haley to show voters he remains a plausible alternative to Donald Trump, political analysts say. The former president comfortably leads in Iowa and in the New Hampshire primary a week later, polls show.

Haley has been surging in the polls in New Hampshire, with a CNN/University of New Hampshire survey from Tuesday showing her at 32% to Trump’s 39%. DeSantis was in fifth place at 5%, behind former New Jersey Gov. Chris Christie and entrepreneur Vivek Ramaswamy.

Haley likely will pick up even more voters after Christie, the harshest critic of Trump on the GOP side, dropped out of the race Wednesday night.

“It makes it easier for Haley to say next week, ‘It’s either Trump or me in New Hampshire,’” said Dante Scala, a political scientist at the University of New Hampshire. “Even though Christie is not offering an endorsement, at least not yet, Haley becomes the only game in town for anti-Trump voters.”

Christie said in his withdrawal speech, “I would rather lose by telling the truth than lie in order to win. And I feel no differently today because this is a fight for the soul of our party and the soul of our country.”

He also was caught on a hot mic saying that Haley is “going to get smoked” and that DeSantis called him, “petrified.”

“I agree with Christie that Nikki Haley is ‘going to get smoked,’” DeSantis wrote on social media afterward.

DeSantis takes sharper aim at Trump in Iowa but to little avail

With New Hampshire looking like a lost cause for DeSantis, the Iowa caucuses have become all the more crucial.

A Civiqs/Iowa State poll released Thursday had DeSantis tied for second in Iowa with Haley at 14% each. But a new Suffolk University poll of Iowa had Haley at 20% and DeSantis at 13%, a concerning swing for the Florida governor.

With Christie out of the race, however, the Suffolk poll shows Christie’s 2% of voters all going to Haley. The Iowa State poll also had most of the 4% in Christie’s camp listing Haley as their second choice.

Trump, meanwhile, remains well in the lead in both polls, at 54% and 55%, respectively.

DeSantis has spent huge amounts of both time and money in the state, visiting all 99 counties and jetting to Des Moines for a Fox News town hall on Tuesday just hours after his State of the State Address in Tallahassee amid a major Florida storm that led him to declare a state of emergency.

“[Iowa is] someplace where he actually invested the time and money and made sure that caucus-goers got to meet him personally,” said Gregory Koger, a political science professor at the University of Miami. “If Iowans who are facing a barrage of television [ads] and personal time with Gov. DeSantis say, ‘I don’t think so’? That’s a really, really damaging outcome for the rest of his campaign.”

Dave Peterson, a political scientist at Iowa State University, said the situation for DeSantis in Iowa differs from the narrative that he’s running an intensely focused campaign.

“I still see stories about his supposed ‘ground game,’” Peterson said. “But I haven’t seen much evidence for that. I was just at the dentist with daytime TV on and I saw more Ryan Binkley ads than I saw DeSantis ads,” referring to an obscure GOP candidate. “[DeSantis] just does not seem to be running an effective campaign here.”

Haley and DeSantis knew the stakes were high Wednesday when they faced off in a testy, one-on-one CNN debate where they spent much of the two-hour event swapping insults.

“She blames other people,” DeSantis said of Haley. “Leadership is about getting things done. Stop making excuses. Make it happen.”

“If leadership is about getting things done, how did you blow through $150 million in your campaign, and [you’re] down in the polls?” said Haley, who referred repeatedly to her website DeSantislies.com. “You’ve campaigned for president in one state. You’re invisible in New Hampshire, you’re invisible in South Carolina … Why should we think you can manage or do anything in this country?”

Haley and DeSantis tear into each other’s records in a hostile head-to-head Republican debate

If DeSantis does finish ahead of Haley, even narrowly, “at least then he has a viable argument, and there’s a rationale to keep going at that point,” Peterson said. “I think his strategy right now just seems to hope something bad happens to Trump and that he’s in the position to pick up the pieces.”

If he finishes behind Haley, he said, she would become the heir apparent if Trump faltered, not DeSantis. At that point, he said, it may be time for him to drop out, Peterson added.

“If he’s third, why would the party turn to him?” he said.