If Matt Bevin wins today's Kentucky gubernatorial election, it will be in no small part due to a unique advertising campaign informing voters of Andy Beshear’s stance on transgender athletes unfairly outcompeting girls in sports.

Kentucky Gov. Matt Bevin should cruise to victory in a state that went for Donald Trump by 30 points in 2016. But can one of the most unpopular governors in the United States win reelection? Bevin’s approval rating remains mired in the mid-30s, with disapproval consistently over 50 percent. Today, voters will choose between him and Democrat Andy Beshear, the son of a popular former governor.

Most of the advertising for Bevin has focused on Trump — he’s with him — and issues such as immigration, the opioid crisis, and abortion. But if Bevin does win today’s election, it will be in no small part due to a unique, targeted advertising campaign informing voters of Beshear’s stance on transgender athletes unfairly outcompeting girls in sports.

This may not be an issue of top priority to voters, but it effectively highlights Beshear’s ideological distance from the typical voter in Kentucky. When deployed to a scientifically identified group of voters, it tips a substantial portion of them into Bevin’s column.

We recently tested messages for the Campaign for American Principles and found that focusing on Beshear’s support for “a law that forces all female sports teams to allow men and boys to compete against women and girls” moves voters to Bevin in a big way. Exposing voters to the “transgender sports” message boosts Bevin’s two-party support by +10 points overall, from 46 percent to 56 percent. The best persuasion targets move +18 points, from 43 percent to 65 percent support.

We tested these messages using randomized-controlled experiments — just like a clinical drug trial, but with ads instead of pills — and survey respondents matched to hundreds of voter file and consumer data points on each individual. We then use these data and machine-learning algorithms to predict how the message is likely to affect every voter in Kentucky, and identify the best persuasion targets on the voter file.

Ads based on this research have been delivered to the most persuadable voters we identified, and the results in the field back up what we found in our research: Educating voters about the transgender sports issue works. The ad firm ran its own test of ad effectiveness in the field and found the best versions boosted support for Bevin +10 points after exposure, compared with a control group that did not see the ads.

While public support for gay marriage has risen steadily over the years, the overwhelming majority of Americans agree — 57 to 20 percent — that transgender females (biological males) have a competitive advantage when competing against biological females in sports. Most voters see this as an issue of fairness, not tolerance or accommodation.

When we conducted our experiment, Bevin’s chances looked decidedly dicey. He was losing a lot of voters who should be with him and was down 46 to 54 percent compared to Beshear in our control group. But Bevin’s problem also holds out a lot of hope for his reelection. Those voters had little negative in mind about Beshear, the well-known and well-liked last name many voted for when his father ran for governor just eight years back. Most of those voters didn’t know that this Beshear is not like his father, and is in line with most other Democrats: a liberal politician who puts leftist ideology above what’s fair for girls in Kentucky.

The most recent poll in Kentucky from mid-October puts the race tied at 46 to 46 percent, with a good chunk still undecided. While undecided voters typically break against the incumbent, our research shows instead that Bevin had a lot of room to grow his support as voters discovered just who the alternative really is.

Bevin may be disliked, but so was Trump when he was elected president in 2016. The alternative makes all the difference in an election. And the Campaign for American Principles has made sure voters know exactly what choice they face in today’s election.