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The polls are open in Kentucky and Senate Minority Leader Mitch McConnell is expected to beat his tea party challenger, Matt Bevin. But, it's been a divisive primary and Bevin says the nasty race will make it difficult for McConnell to beat the Democrat in the November race, Secretary of State Alison Lundergan Grimes.

"My job is to beat him," Bevin told ABC's Louisville affiliate WHAS. "And if we don't, I don't know how he wins in November when he's divided his own party as much as he has."

The margin this evening will be important to watch and may reveal if Bevin is correct. McConnell will need Bevin's voters to back him if he is to beat Grimes in November.

Bevin acknowledged to WHAS' political reporter Joe Arnold that he will support McConnell if he is victorious tonight, as is expected.

"I've never supported a Democrat over a Republican in any race," Bevin said. "I don't intend to start on this race or any time in any other race in the foreseeable future."

The most recent poll in the race from NBC News/Marist earlier this month shows McConnell, the Senate minority leader, leading Bevin by 32 points. The numbers between McConnell and Grimes, though, are much tighter with McConnell beating Grimes by just one point, within the margin of error.

The McConnell versus Bevin primary has been a divisive one, but it was also supposed to be a much closer race. With McConnell's declining approval ratings with Kentucky voters and Bevin's personal fortune - as well as support and money from national tea party groups - it was supposed to be a much tighter primary. Bevin had no political experience and turned out to be more of a flawed candidate than expected, making several serious campaign errors. In past divisive primaries in the state, including the 2010 face off between Rand Paul and Secretary of State Tray Grayson, when Paul won it was McConnell who helped mend the party, despite his support for Grayson.

After tonight, attention will turn to the general election where the likely McConnell versus Grimes brawl will be the most closely watched race in the country and could very well impact which party takes the Senate in November.