DUBUQUE, Iowa (AP) — Second place in the Iowa caucuses is seldom so important.

The rivalry between GOP presidential candidates Ron DeSantis and Nikki Haley has become a leading storyline before the first Republicans vote on Jan. 15. The two are in an increasingly testy contest to emerge in Iowa as the preferred alternative to former President Donald Trump for the party’s 2024 nomination.

Florida Gov. DeSantis has said he expects to win Iowa despite trailing far behind Trump in polls. He portrays Haley, a former South Carolina governor who was Trump’s U.N. ambassador, as a puppet of wealthy donors and someone who has flip-flopped on key issues.

Haley, who hopes to edge the better-organized DeSantis in Iowa, has accused him of misrepresenting her record, especially on taxes, and of falsely portraying himself as tough on China.

The stakes are enormous for both.

DeSantis would upend the race if he were to beat Trump in the caucuses. Haley’s allies believe they could hobble DeSantis if she finishes ahead of him. The thinking is that a second-place finish would give her a boost before New Hampshire’s Jan. 23 primary and a chance to take on Trump directly in South Carolina a month later.

“I don’t know if we’ll get to second. I certainly hope so. That’s our mission,” said Mark Harris, lead strategist for Stand for America, a pro-Haley super political action committee. “We do that, we turn the page and head into a state where I think we’re in a great position to win.”

Trump has been operating at a different level, attracting tens of thousands to rallies in larger cities since the fall and packing events into the final stretch of the campaign in every corner of the state. His campaign has spent months organizing caucusgoers and recruiting “captains” responsible for turning out voters on Jan. 15.

He has ramped up his attacks of Haley in speeches and campaign ads, which Haley has said is a sign he is taking her more seriously. Before a Trump speech Friday, her campaign issued a statement about the former president going after her on immigration.

“Nikki Haley is rising,” her campaign said. “Donald Trump is scared. This is a two-person race.”

But Haley must also fend off DeSantis. His camp has hit her for several recent comments about the cause of the Civil War and the role of Iowa in the GOP nomination process. In an interview with NBC News and the Des Moines Register, DeSantis referred to Haley as a “phony.”

DeSantis has repeatedly mentioned comments Haley made in New Hampshire this past week when she suggested that New Hampshire voters would “correct” Iowa’s results. Haley tried to play down the remark by explaining it as a nod to the good-natured rivalry between the two early-voting states.

“We’re getting down to crunch time in the Iowa caucuses,” DeSantis told more than 300 people jammed into a bar Saturday in downtown Dubuque. “And no, your votes don’t need to be corrected by any other state. I don’t care what Nikki Haley says.”

Haley answered a recent question in New Hampshire about the cause of the Civil War without mentioning slavery. She walked back her answer a day later and said “of course” slavery was a cause of the war.

The Civil War comment came up again at a CNN town hall Thursday. DeSantis’ campaign posted on X, formerly Twitter, an excerpt of Haley’s response, in which she said she had “Black friends growing up.”

While the original remark prompted rebuke from Democrats and GOP rivals, especially former New Jersey Gov. Chris Christie, who mentioned that South Carolina was the first state to secede from the Union over slave rights, the dust-up never came up in questions at four Iowa events the following weekend.

What Haley did mention at an event Friday, as she has regularly in recent weeks, is an ad aired by a DeSantis-aligned super PAC in which she is accused of flip-flopping on a pledge not to raise the fuel tax while governor of South Carolina.

“Every one of those commercials is a lie,” she said. She said she resisted gas tax-increase proposals until she offered a compromise to proponents that came with an even larger income tax reduction. The proposal died without action.

DeSantis has shaken up his campaign staff and recalibrated his message several times over the past year and has bet heavily on a strong Iowa finish. He visited all 99 counties, aided by an aligned super PAC, Never Back Down, that spent the summer and fall sending organizers door to door to recruit supporters.

Haley’s team began organizing much later and only last month received the endorsement of the political arm of the billionaire Koch Brothers’ Americans for Prosperity. That group is now canvassing voters and organizing for Haley.

Still, the pro-Haley super PAC Stand for America has emerged the biggest spender down the stretch, purchasing more than $27.5 million in ads since the start of last year, according to the media tracking firm AdImpact. Two DeSantis-allied groups, Never Back Down and Fight Right, have combined to spend about $26 million over the same period.

Former Iowa Gov. Terry Branstad, a Republican who has not endorsed in the race, described Haley’s comment about Iowa an unfortunate mistake, but not one that would likely derail her campaign. His successor, Gov. Kim Reynolds, has endorsed DeSantis.

“Second is a possibility. If she gets second here, there would be tremendous momentum going into New Hampshire,” Branstad said Friday at an event where Haley was speaking. “It’s going to be difficult because DeSantis has spent a lot of time here and has the governor’s support.”

Candidates running in Iowa work to show respect for the state’s traditions and its leadoff status, though some question Iowa’s ultimate influence. The last Republican to win a contested caucus and become the GOP nominee was George W. Bush in 2000.

“You can’t be antagonistic or dismissive of people whose votes you want,” said Ellen Carmichael, a Republican campaign messaging strategist who has worked on presidential campaigns. “To me, that was just such an unforced error. They take it seriously, with such reverence for the system. You don’t want to diminish that.”