At the beginning of the year, his seat was considered safe for the Democrats. Given the demographics of the state, you have to move this one from lean Democrat to lean Republican.
UPDATE: Barone weighs in:
Going into this cycle, [Bayh] looked like a sure bet for reelection.
Where does this leave Democrats in the 2010 Senate contests? Not in very good shape. The North Dakota seat held by Democrat Byron Dorgan seems sure to go to Republican John Hoeven. The Delaware seat held by Ted Kaufman (appointed to replace Joe Biden) seems very, very likely to go to Republican Mike Castle. The Indiana seat held by Bayh seems now very likely to go to a Republican.
Read the whole thing!
UPDATE FROM BRUCE (GayPatriot): Word is coming from Maryland that US Sen. Barbara Mikulski is also going to retire in the next few days. Tsunami.
UP-UPDATE (from Dan): Let’s hope Michael Steele runs for the open seat.