Yesterday's FISA legislation passed the House without a majority of support from Democrats, who opposed the measure 105-128 in spite of the votes of Reps. Pelosi and Hoyer. A notable exception however were Democrats in competitive districts.
The Cook Political Report counts 31 incumbent Democrats as being in potentially competitive House districts, not including those who are retiring. Here is how that group of 31 voted on the legislation:
That is 23 Yeas against 8 Nays; included among the Yeas were all 6 incumbent Democrats in districts rated as "toss-up". By contrast, those Democrats in noncompetitive districts (or those who are retiring) voted against the measure 82-120. A special star of sorts should go to IN-9's Baron Hill, who was the only Democrat in a competitive Red State district to oppose the measure. Hill has run for the House five times, winning on four occasions, but never by more than 25,000 votes.
Now, one should be careful about conflating cause and effect. Did these Democrats vote for the FISA bill because they think it will help them to get re-elected? Or were they elected in 2006 because they were conservative enough Democrats to vote for this legislation in the first place?
Either way, this certainly helps to explain Nancy Pelosi's mindset.
As for Barack Obama, I'm not sure that he had much choice but to come out in support of the legislation. Was he really going to throw Nancy Pelosi under the bus and pick an intraparty fight when she was as instrumental as anybody else in Washington in getting him the nomination? Was he really going to run afoul of the Blue Dogs when they are probably his swing voters in passing some version of national health care legislation?
This was certainly a political decision on Obama's part -- but not necessarily one that had very much to do with his own electoral prospects. The FISA issue simply isn't high-profile enough to register at the national level. Instead, it was a decision made with the politics of governance in mind: not a 2008 decision, but one for 2009.