Democrats who voted against ObamaCare are now explaining why they voted for it

John Merline has done a real service getting the explanations offered by Democratic Congressmen for why they voted against ObamaCare and have now this week voted for it. My problem is that only a couple of these statements really explain the change in their positions. If you take their statements as true, they should have voted for ObamaCare the first time around. For example:

John Barrow, D-Ga.: "We need to keep the parts that prohibit folks from getting denied coverage based on pre-existing conditions, and extend health coverage to kids just out of college. ... There are a lot of good things in the bill," he said Saturday at a meeting with constituents. "I don't believe in voting against the parts that are good. ... We need to amend it, not end it."

If Barrow doesn't believe in voting against the good parts of the law now, why did he vote against them previously?