We just shot today's episode of TPMtv, which is a run down of the big senate races. This won't surprise anyone who's closely watching the senate races. But if you've only been watching the presidential race, it's all going to come down to three southern state races, all of which share a strong basic profile -- Kentucky, with incumbent Mitch McConnell, Georgia with incumbent Saxby Chambliss and Mississippi, with appointed incumbent Roger Wicker.

None of the three Dems in these races has yet to get a public poll putting them in the lead. But each is very close, within a few points. And the incumbent, in each case, is under 50%. All of which is to say that each of these incumbents is in real trouble, though each probably has a thin advantage going into election day.

To get to 60, the Dems need to bag one of these three seats. Even with that, they'd need to pull out the Minnesota race, which looks promising but is still touch and go, and win all the ones where they're favored but it's still close. But when you're watching on election night, keep an eye on those three races. They'll be the tell.