Can John Kerry hold on to his lead? Harold Wilson, that British politician more canny than admired, usefully reminded his audience that things can change very quickly in politics. "A week is a long time," he said, in politics, and we have seen this over and over in the American scene these past months. After all, only nine weeks ago former vice president Al Gore blessed the insurgent campaign of Howard Dean and most pundits thought the race was over. All that was needed was the anointing of the former Vermont governor as Democratic party standard-bearer to take on US...