Which Kentucky Democratic primary candidate is best positioned to challenge Mitch McConnell in November 2020?

Senator Mitch McConnell

There are ten Democrats vying for the honor of challenging incumbent Senator Mitch McConnell this fall. The three most prominent are Amy McGrath, a retired Marine Corps Lt. Colonel who narrowly lost a 2018 challenge to incumbent Congressman Andy Barr in Kentucky’s 6^th district, Kentucky State Representative Charles Booker, and Marine Corps veteran Mike Broihier.

Amy McGrath

In a recent debate, McGrath presented herself as an electable moderate who can appeal to Trump voters while Booker and Broihier hammered her for these moderate positions and presented themselves as solidly liberal alternatives. While there is, again, a conspicuous absence of head-to-head polling in this race, McGrath is heavily favored to win due to her name recognition and fundraising advantage, as well as her strong endorsement by the DSCC. That said, Booker’s profile has risen in recent days due to his visible participation in the ongoing protest events in Louisville surrounding the deaths of George Floyd, Breonna Taylor, and others.

Charles Booker

All three argue that they are the best bet to beat McConnell this fall, and have drawn attention to the smattering of polls from January that show McConnell and McGrath or a generic Democratic challenger in a statistical tie.

Mike Broihier

The fundamentals are that partisans tend to vote for their party’s candidate in federal-level elections, and roughly 53% of Kentucky voters identify as Republicans or Republican-leaners. Assuming this pattern holds, the Democratic Senate nominee will need to persuade and mobilize the handful of voters who identify as pure Independents as well as a critical mass of Kentucky Republican voters, 90% of whom have a favorable view of Donald Trump, in order to win.

There is some recent precedent for this. Last year, Democratic Governor Andy Beshear won an extremely narrow victory over unpopular Republican incumbent Matt Bevin by, in part, winning 16% of Republican voters. This may not be a “perfect parallel,” though, as Perry Bacon Jr. has written, “because governors races tend to be more localized and Senate races more nationalized. In 2016, every U.S. Senate election was won by the same party that won the presidential race in that state.”

The key question, I think, will be whether Kentucky Republican voters see Mitch McConnell as more like Trump (who they like a lot) or more like former Governor Matt Bevin (who they didn’t like as much). If they see McConnell more likely they see Trump, he’ll probably have a relatively easy path to reelection. If they see him more like Bevin, though, then the Democratic candidate might have a shot if he or she can peel off some Republican voters. Which candidate is best poised to do that?

A 2019 Kentucky exit poll fielded by yours truly and a collaborative of political scientists from institutions around Kentucky showed that among these 16% of Republican voters who crossed party lines to vote for Andy Beshear, 42% said they had a very/somewhat favorable view of Joe Biden and 27% said the same about Bernie Sanders.

Now, Biden and Sanders are not the same people as McGrath, Booker, and Broihier. That said, if Kentucky voters are thinking in terms of ideological lanes and strategy styles, Biden and McGrath both present themselves as pragmatic moderates and Sanders, Booker, and Broihier present themselves as more consistent ideologues.

If (and it’s a big IF) those same Republican-Beshear voters think about the Senate race the same way they did about the governors race last year, this would suggest that McGrath has an edge over Booker or Broihier in attracting Republicans who might be willing to cross party lines, as they more of them view Joe Biden favorably compared to Bernie Sanders.

Digging even deeper, this same exit poll shows that among Kentucky Republicans who have a favorable view of Donald Trump but an unfavorable view of Mitch McConnell, 22% view Biden favorably compared to 16% who view Sanders favorably. Again, assuming that they view the Senate race the same way they did about the governors race last year, McGrath has a very small edge in the likelihood of attracting Republican voters  who like Trump but not McConnell.

The bottom line? This November, most Kentucky Republicans will vote for McConnell and most Kentucky Democrats will vote for the Democratic candidate, regardless of whoever wins the primary election this month. All three leading Democratic primary candidates would have a shot of peeling off the Republican votes that they would need to win, but the exit poll shows some evidence that, all other things being equal, Amy McGrath might be able to peel off a few more than either Charles Booker or Mike Broihier.