And he'll certainly have to. Polls have consistently shown McConnell with abysmal approval ratings, and in dark red Kentucky, that's kept him under 50 percent in hypothetical head-to-heads with Grimes. The question is whether Grimes will be able to retain enough crossover appeal to win what is already a vanishingly small group of undecideds to her cause, because there simply aren't enough reliably Democratic voters in the state to win with the base alone.
For Grimes, though, this race amounts to something of a free shot, since she's not up for re-election until 2015 and doesn't have to give up her current job to challenge McConnell. And while Democrats have usually done less well in midterms than in presidential years, the calculus may be different in Kentucky, where Grimes won't have to contend with an unpopular President Obama at the top of the ticket.
Make no mistake: This will be an incredibly difficult contest. Grimes will have to raise a ton of cash and be ready to weather the McConnell attack machine for a solid year-and-a-half. McConnell certainly won't lack for funds, and what he lacks in popularity he'll make up for in brutality. But Grimes gives Democrats a real chance at an upset, and the very fact that she'll force McConnell to run a real campaign means Republicans will have a harder time trying to take back the Senate. And a Grimes victory? That would be the sweetest of all.