Its power is often underestimated in our politics. But it can make a big difference. Imagine if Kerry had voted what was almost surely his conscience on Iraq (thus doing the right thing in his own mind), and opposed authorizing the war. He would have been stronger during the primaries and stronger now that he seems to be making the calculation that opposing the war four-square (more or less, or as four-square as he ever gets) is the soundest play for him.