Polls are showing that both Obama and Biden's old Senate seats may fall to Republicans in 2010. In Illinois, Rep. Mark Kirk, a centrist Republican, is leading his Democratic adversary pretty handily already, while Rep. Mike Castle, long Delaware's lone House member, is polling well ahead of Joe Biden's son Beau, his potential Democratic opponent. Combine those with potential losses for Chris Dodd and Harry Reid, and the Senate could have a vastly different flavor this time next year.