South Dakota's incumbent Gov. Larry Rhoden and businessman Toby Doeden, a self-described political outsider, will advance to a runoff for the Republican nomination for the state's governor, CBS News has projected.

A July 28 runoff election is necessary because no candidate in Tuesday's GOP primary is on track to win 35% of the vote. 

The competitive and frequently contentious primary included the sitting governor, a congressman and a state legislative leader.

Doeden was the top vote-getter in Tuesday's primary, with Rhoden in second place. Rhoden was the state's lieutenant governor until he was elevated to the state's top job when President Trump picked then-Gov. Kristi Noem as homeland security secretary last year.

Rep. Dusty Johnson and South Dakota House Speaker Jon Hansen were also on the ballot on Tuesday. 

The eventual nominee will face Democratic former state Sen. Dan Ahlers, who ran unopposed for his party's nomination. Democrats have not controlled the South Dakota governor's mansion since the 1970s, and this year's race is expected to strongly favor the Republican candidate.

Rhoden has touted his record in South Dakota politics, highlighting a series of bills he signed earlier this year that lower property taxes in the state and a plan to replace the state's prison. He has also talked up the state's economic performance and argued things are going well, saying in one campaign ad: "Some folks want you to think South Dakota's broken. It's not."

Doeden owns car dealerships, rental properties and other investments in South Dakota, and has lent his campaign roughly $4 million. On the campaign trail, he has pledged to phase out property taxes and slash spending, and has railed against "career establishment politicians," arguing the state's economy is not performing as well as it should.

The primary had grown bitter in its final months. Doeden and Johnson criticized Rhoden and Hansen for green-lighting increases in state and county sales taxes to pay for a slate of property tax cuts, and a political action committee called Rushmore Principles spent upward of $1 million on anti-Rhoden advertising that focused partly on the sales tax issue. 

Hansen and Rhoden have defended the tax legislation and accused Johnson of misrepresenting it. Rhoden has also alleged that Johnson — whom he has branded a "Washington politician" — is behind the group's attack ads, which Johnson denies.

Meanwhile, Doeden and a political action committee that supports him accused Johnson of being insufficiently supportive of Mr. Trump while in Congress, and Johnson argued Doeden's push to eliminate property taxes is unrealistic.

Mr. Trump, who won South Dakota by a 29-percentage-point margin in 2024, has not endorsed a candidate in the gubernatorial race.