An opportunity for political mischief
I just noticed on that Feinstein amendment (link below) that all the Democratic Senators running for President missed the vote: Edwards, Kerry, Graham and Lieberman are all missing in action. The vote was very lopsided with the amendment rejected 60-35, so maybe the Senators saw no point in showing up to their jobs that day.
The Republicans ought to have some fun with this chronic truancy among the Dem Senators. Make sure the Donks are all in Iowa or New Hampshire (far away from the Senate floor) then tailor the votes so they are within the difference of the missing senators. Thus, if the Feinstein vote was, say, 49-47, the talking heads can say: "That motion could have passed, if only those Senators had shown up. Too bad."