You'd think Reid would want to bring it to the floor if for no other reason than to do the same thing to Romney that we are currently doing to him: bringing up a previous position to highlight the flip flop.
And the thing with the senate is that many of them were in "wait and see" mode with HR 459. Same with the house leading up to yesterday. And some cosponsors may have signed on to please their constituents, but with a little arm twisting by Bernanke, voted NAY. Some Dems vote AYE to get the independent vote in their districts. I remember last time, Pelosi waited till she was sure a certain bill wasn't going to have the votes to pass, then gave permission to the reps in heavy GOP distircts permission to vote AYE. That's why sometimes, when you're watching the vote count on C-SPAN, there are a bunch of hold-outs till the outcome is certain, then they all vote according to how it will benefit them for reelection in their own districts.