I can't believe I'm saying this but I really think Republicans have a chance to win back the Senate this fall now.
Let's be realistic- there was a Rasmussen view of Indiana that showed Evan Bayh down to Mike Pence and barely up on John Hostettler and a Research 2000 view that showed him safe for reelection. If the latter was the real state of things I don't think Bayh would be dropping out this late in the game. I have to think he knew he had a really tough fight on his hands and he didn't have the stomach for it, just like what happened with his decision not to run for President in 2008.
So I think the GOP will be favored in Indiana however the candidate field shakes out this week, and I think the GOP is favored in Arkansas, Nevada, Colorado, Pennsylvania, Delaware, and North Dakota as well. Win all those and you have a 52-48 Democratic Senate. Beyond that you have Illinois looking like a toss up and then California and New York looking like they definitely have the potential to become highly competitive based on the incumbents' lack of popularity and Washington and Wisconsin as maybe the longest shots for the GOP but possible with an A list candidate.
And really, if it's a 50-50 situation does anyone trust Joe Lieberman not to throw his hat with the Republicans? Three months ago I would have said Republicans have about a 5% chance of taking back the Senate. Now I'd put it more in the one in three chance range, and rising by the week. And who knows when the bad news for Democrats will stop pouring in...