Earlier today I posted my prediction that the Democrats would barely hold on to the Senate. Ben Nelson of Nebraska must have seen my analysis, because he's hanging it up.
The 70-year-old conservative Democrat, whose seat is being heavily targeted by Republicans in 2012, said in a statement that “while I relish the opportunity to undertake the work that lies ahead, I also feel it’s time for me to step away from elective office, spend more time with my family, and look for new ways to serve our state and nation.”
Nelson is on the conservative fringe of the Democratic Party and not very well liked by progressives; in particular, while Republicans think his vote for the Affordable Care Act would have given them a weapon to use against him, it's also true that Nelson held out his vote for as long as he could to make the Affordable Care Act the shittiest deal possible. It wasn't until Scott Brown gave the Republicans enough votes to hold up a filibuster that he stopped the crap and got in line. (Also, as msmacgyver points out below, Nelson joined Republicans in blocking extension of unemployment benefits, presumably because he was going for an award from the dick-of-the-month club.)
The bad news for Democrats is that they have nobody who can credibly run in Nelson's place (although I hold some hope that Scott Kleeb will try again). The GOP had a good shot of flipping this seat before, but it's a mortal lock now. The worse news is, this frees up Republican money to pursue seats elsewhere, such as Montana, Missouri, or North Dakota. I still think a complete GOP takeover is unlikely - they'd have to net four seats - but it just got a little more likely today.
UPDATE Love this: