Moscow is not a city of ghosts, but on Saturday, tens of thousands of figures were seen marching in the Russian capital chanting, "We exist! We exist!" That might seem like an exercise in the obvious. But the crowd thought a reminder was in order for Prime Minister Vladimir Putin, who has generally regarded his critics as though they were invisible. He can see them now. In last week's parliamentary election, his United Russia Party suffered a humiliation, losing 77 of its 315 seats and getting less than a majority of all votes—down from 64 percent four years ago. It's embarrassing enough to do poorly in an honest election, writes Steve Chapman. Putin's party managed to crater despite vigorous measures to rig the vote.