Kentuckians on Tuesday will go to the polls in their state’s gubernatorial primary, with GOP voters deciding who challenges the state’s popular Democratic governor, Andy Beshear, this November.

In the Republican primary, Attorney General Daniel Cameron and a former ambassador to the United Nations, Kelly Craft, are seen as having the best shots to win in a field of 12 candidates. Behind the frontrunners, the agriculture commissioner, Ryan Quarles, and attorney Eric Deters are the most competitive candidates.

A professor of political science at the University of Kentucky, Stephen Voss, tells the Sun that each candidate would “bring notably different attributes in a race against Beshear,” but all of them face “an uphill climb” in the general election.

“Republicans see this election as their opportunity, and Governor Beshear’s victory is seen as fluke. Every ambitious Republican saw this election as the right time,” Mr. Voss said. “I don’t think Beshear’s popularity is an error or a fluke.”

According to an Emerson College survey, Mr. Cameron is the favorite, though no candidate is even close to polling at a majority of the vote. The survey found that Mr. Cameron is polling at 33 percent support, with Ms. Craft at 18 percent, Mr. Quarles at 13 percent, and Mr. Deters at 10 percent.

Mr. Cameron has had his chances boosted by President Trump’s endorsement, a nod Mr. Cameron has not been shy about touting despite Mr. Trump’s considerable baggage.

“Tonight’s message to Kentucky from President Donald J. Trump is clear,” Mr. Cameron said Sunday. “There is only one candidate in this race who will be the conservative warrior Kentucky needs.”

According to the executive director of Emerson College Polling, Spencer Kimball, Mr. Trump’s endorsement appears to be growing in importance as the election draws closer.

“The Trump endorsement’s impact has increased since last month — 48 percent of Republican voters say Trump’s endorsement of a candidate makes them more likely to vote for that candidate,” Mr. Kimball said.

According to Mr. Kimball, 41 percent of GOP primary voters said the endorsement didn’t affect their decision and 12 percent said it made them less likely to support Mr. Cameron.

In Kentucky, whoever wins the most votes in the primary will be named the GOP’s nominee for governor, even if that candidate does not win an outright majority.

Although Kentucky is a friendly state to Republicans, winning the general election might be a taller task for the GOP nominee than it seems on first blush.

Mr. Beshear is among the most popular governors in the country, according to a survey by Morning Consult conducted earlier this year. In it, he enjoyed a 63 percent approval rating.

This probably puts Mr. Beshear in a stronger position than he found himself in during the 2019 gubernatorial race, when he defeated the incumbent Republican governor, Matt Bevin, by just more than 5,000 votes.

Since that election, though, Mr. Beshear’s popularity has risen. He has gained support from voters in the eastern and western portions of the state due to his response to recent flooding and tornados in those areas.

Mr. Beshear also enjoys support in Kentucky’s Golden Triangle, the region between Lexington, Louisville, and Cincinnati that was historically Republican-leaning but has been trending toward Democrats since 2018.

Many Kentucky voters, according to Mr. Voss, may vote for Republicans like Senator McConnell or President Trump on the national level but don’t see themselves as Republicans — especially newer, lower-income GOP voters. Mr. Cameron, who enjoys the support of Messrs. McConnell and Trump, could run as a GOP unity candidate.

“Cameron has one foot in the state’s mainstream Republican Party and the other foot firmly in the Trump camp,” Mr. Voss said. “Cameron seems to have a head start in being positioned to be a unity candidate.”

It’s also not clear that any candidate would have a distinct advantage over Mr. Beshear in the general election, Mr. Voss said. Democrats, in a reversal of the national trend, tend to see performance improve in low-turnout elections in Kentucky as well.

“The problem is any candidate will struggle to get voters interested in an off-year election,” Mr. Voss said.