Oh cool, according to that wiki link and the corresponding page of gay marriage opponents, a plurality of Senators now support SSM (43 in favor, 41 opposed).
UPDATE
I sperg'd out and actually researched it. Actual breakdown is as follows:
Democrats:
45 Supporters
6 Opponents (Donnelly, Manchin, Heitkamp, Johnson, Nelson, Pryor)
4 Ambiguous (Casey, Hagan, Landrieu, Tester)
Republicans:
1 Supporter (Portman)
42 Opponents
2 Ambiguous (Collins, Kirk)
Notes:
- I counted Carper, Kaine, and Rockefeller as supporters; they haven't explicitly endorsed gay marriage, but have made statements that make their beliefs somewhat obvious (and all three signed onto an amicus brief arguing that DADT be overturned in full)
- Hagan and Tester both sound like they'd be obvious supporters of gay marriage if they didn't have reelection concerns
- Landrieu avoids making any statements on the issue at all costs
- Casey looks to be in the middle of an "evolution" on the issue and is clearly hoping the Supreme Court solves everything so he won't have to make any difficult votes
- Donnelly sounds like he's beginning an "evolution" of his own
- Heitkamp would probably support gay marriage if she was from a liberal state; the other five Democratic opponents appear to genuinely oppose it on principle
Also here's a map!
30% shade means one Senator from the state has an ambiguous position. Gray states have one Senator in support and one opposed. (errors possible, I made the map pretty quickly)
