Josh Marshall’s thinks money has played a major role:
The word has clearly gone out that if you want to fund a Senate campaign in the Democratic Party, you have to get right on Marriage Equality. Period. If you’re not, the funder class just will not be there for you, not to mention the grassroots Dems who give their $50 and $100 checks. Again, I don’t think this is a bad thing at all. But if you’re looking to understand the avalanche that is a big part of what’s driving it.
I’ll take it, depressing as it is.