Kentucky Republicans have longed to take over state government, and they'll find Tuesday in a GOP primary what it takes to do that. 

Of the 28 governors since 1900, 22 have been Democrats. Their paths to Frankfort have been marred by fierce primaries that deeply split the party, only to regroup and trounce the Republicans in November. 

But this year, it's the Republicans' turn to scrape for every vote in a divisive primary where the winner may have less than 30 percent of the vote while the Democrats coalesce around a likely nominee who has breezed through the primary season with minimal opposition. The question is: Who can survive the primary without sustaining so much damage they pose no threat to likely Democratic nominee Jack Conway in November? 

Will it be James Comer, the state agriculture commissioner and the only candidate who has won statewide office and has raised more money than Conway in some fundraising periods? Will it be Hal Heiner, who narrowly lost a race for mayor of Louisville in 2010 and could eat into Conway's margins in the state's largest city that has been a strong Democratic base for decades? Or will it be Matt Bevin, the Louisville businessman who excites the party's more conservative wing but has yet to show he can win statewide after getting trounced by U.S. Sen. Mitch McConnell in last year's primary? 

Former Supreme Court Justice Will T. Scott is also running but has fallen behind in recent public polls. 

"It's been the dirtiest campaign that I've ever witnessed in Kentucky history," Comer said. "But I believe that I will be able to unite the party." 

The campaign intensified two weeks ago when Marilyn Thomas wrote a letter to the Courier-Journal accusing Comer of emotionally and physically abusing her when the two dated while attending Western Kentucky University in the early 1990s. 

Comer has denied the allegations, but he blames Heiner's campaign for spreading the rumors following Heiner's public apology after the Lexington Herald-Leader revealed Heiner's campaign had communicated with a blogger that had been pushing the story on social media for months. 

Things escalated Friday when Heiner, after vowing he would not mention the abuse allegations, aired a TV ad based on them. 

"There's certainly been some political turmoil over the last three weeks," Heiner said Monday. "But I believe the overriding concern, I hear it all the time, is that Kentucky is not where we can be. I believe when people go into the polls Tuesday and they decide to pull that lever, it will be based on that issue." 

Comer and Heiner were seen as the front runners early in the race, based on Comer's status as the state's only Republican executive officeholder and Heiner's personal wealth that allowed him to outspend everyone on TV ads. But Bevin has made a strong push in recent weeks, emphasizing the tensions between Comer and Heiner and offering himself as an alternative. Monday, he began airing a 60-second TV ad that touted his jobs plan and ends with: "I'm Matt Bevin, and I would be grateful for your vote." 

The polls are open from 6 a.m. to 6 p.m. local time.