Sen. Arlen Specter announces he'll become a Democrat, acknowledging his chances of winning the 2010 Pennsylvania Republican primary against Pat Toomey were "bleak."
SEN. KIT BOND: "He chose what he clearly thinks is the easiest path to re-election this time."
SEN. CLAIRE MCCASKILL: "I don't think this will result in big changes on policy. Senator Specter was a moderate and is still a moderate. It will, however, help us get to substantive debate on important issues. It will also be harder for Republicans to block us from even talking about policy."
More from McCaskill from the Wall Street Journal: "It basically is saying moderation is a very difficult thing in the Republican Party. If you are a moderate, you are an endangered species in the Republican Party."