Numbers maven Nate Silver looks at how electoral prospects affected votes on the bailout:
Among 38 incumbent congressmen in races rated as "toss-up" or "lean" by Swing State Project, just 8 voted for the bailout as opposed to 30 against: a batting average of .211.
By comparison, the vote among congressmen who don't have as much to worry about was essentially even: 197 for, 198 against.
...among 26 congressmen NOT running for re-election (almost all of whom are Republicans), 23 voted in favor of the bill, as opposed to 2 against and one abstaining.
There's a huge chance the bailout doesn't work; there's very little chance it makes everything better. As a result it's way, way safer for Congressmen in tight races to vote against the thing.
That said, I do believe there was genuine ideological opposition to the bailout on the left of the Democratic Party and the right of the Republican Party. A host on CNBC postulated that this was a revolt of the Republican rank-and-file who had been told, for many years, that their desire for fiscal conservativism would have to take a back seat to the GOP leadership's spending priorities. I think there's some real truth to that.