8. Virginia (Jim Webb, D, retiring). This seat capped the Democrats’ surprise run at Senate control in 2006 after George Allen imploded by directing a racial slur at an opposition videographer. It may give Senate control back to Republicans in 2012. Allen is back for another swing at his seat, and most polls initially favored him when Webb dropped out. But former Gov. Tim Kaine decided to try for the seat, setting up a tight race.

The polls have shown anything from a seven-point Kaine lead to a five-point Allen lead. This seat likely goes the way of the presidential race. If Romney wins, it means that the state polls were somewhat biased toward Democrats this cycle, which would give Allen the edge. If Obama wins, the state polls were probably correct, and we’d expect Kaine to win. But this one could go either way.

9. Nevada (Dean Heller, R). Democrats had high hopes for defeating the appointed senator, but he hasn’t trailed Rep. Shelley Berkley in a poll since September. Of course, Sharron Angle could have said much the same thing in 2010, and she ended up losing badly to Harry Reid. If the same factors that caused pollsters to under-survey Reid’s numbers (and indeed the entire Republican ticket) are affecting Heller, this could wind up a surprise.