U.S. Senate candidate and Kentucky Secretary of State Alison Lundergan Grimes (D) campaigns in advance of the state's Democratic primary on May 18 at the Maifest festival in Covington, Kentucky. (Photo by Win McNamee/Getty Images)

The Kentucky Senate race comes down this: whether voters are more willing to vote against a Barack Obama who is not on the ballot, or a Mitch McConnell who is.

A Western Kentucky University poll released Tuesday is the latest to show Alison Lundergan Grimes (D) remaining competitive with McConnell, the Republican Senate minority leader. McConnell leads 45-42, within the poll's margin of error. It's the latest poll to show the race is still tight, despite national Democrats having pulled ads from the state.

The most interesting part of the poll, though, is how very few people are actually voting for Grimes. Rather, 60 percent of Grimes supporters say their vote is more about casting a ballot against McConnell than casting one for Grimes. Just 34 percent of Grimes backers said their vote will be more in support of the Democrat.

Voters for McConnell, meanwhile, are much more likely to say it's about supporting the incumbent (62 percent) than opposing Grimes (33 percent).

The Fix does wonder, though, what these numbers would look like if you substituted Grimes's name for another Democrat, President Obama. A recent CBS News poll showed 56 percent of Republicans nationally say their midterm vote will be a symbolic vote against Obama.

That doesn't mean equally as many McConnell backers would say their vote is more about Obama than McConnell. But given the tenor of the race and the repeated attempts by Republicans to tie Grimes to Obama (along with her all-too-telling refusal to say whether she voted for Obama), it's clear that the president is a major subplot of this race.

There's plenty of dislike to go around, though. McConnell and Grimes are underwater as far as their personal images go. While 44 percent of likely voters have a favorable image of McConnell, 51 percent have an unfavorable one. For Grimes, it's a 38/47 split.

When it comes to being unpopular, though, nobody can hold a candle to Obama. His approval rating is at just 30 percent in Kentucky, with 66 percent disapproving -- and 42 percent strongly disapproving.

Given those numbers -- and Grimes being underwater herself -- it would be pretty stunning if Grimes were to pull off the upset. She would be over-performing Obama's numbers in Kentucky by nearly 20 points.

But while Obama is certainly the most unpopular and is undoubtedly a drag on Grimes, he's not on the ballot, and McConnell is. And thus, Obama's drag on Grimes is less directly tied to her showings in the polls than McConnell's poor image is tied to his. In other words, Obama is the most unpopular, but isn't on the ballot; McConnell is quite unpopular, but is. Ipso facto, both men are weighing down their side of the ballot in what are probably pretty comparable numbers. The race is pretty close to tied, after all, and Grimes is very much running as the anti-McConnell.

Whatever the case, it's pretty clear that the Kentucky Senate contest is a race to the bottom, and in politics, getting people to vote against something is much easier than getting them to vote for something.

Come Nov. 4, very few people in Kentucky will be voting for either of the candidates. Instead, they'll be voting against someone -- someone who might or might not be on the ballot.