AT's ace political correspondent Rich Baehr has a piece up at PJ Media that looks at the prospects for a GOP takeover of the senate:

If the GOP won all the closest races - Illinois, Colorado, Nevada, and West Virginia - plus the five in which GOP candidates hold bigger leads, the Republicans would get to 50 Senate seats. Then the Republicans could attempt to persuade Nebraska Senator Ben Nelson to pull a "Jim Jeffords" and switch parties, or get Joe Lieberman to remain an independent but begin to caucus with the Republicans. Both senators face difficult 2012 re-election battles.

But this scenario assumes the GOP gets to 50. I think the odds of that happening are less than 50-50. There have been several recent elections where one party or the other won almost all the close Senate races, and it could happen again. But I think there is a pretty good chance that at least one, and maybe two, among Nevada, Illinois, Colorado, and West Virginia could fall to the Democrats.

My best guess is the GOP gets to 48 or 49 in the Senate, right where most of the analysts are now converging in their forecasts.

Those close races will be decided by turnout. Which party can get their voters to the polls in greater numbers than the other party? We'll find out next Tuesday.