President Putin used to handle such problems more deftly. His is a soft dictatorship, and he has rarely risked his position with mass beatings and bloodshed, or too obvious fraud at the ballot box. The phony election results of 2011 were a clear exception, but the government dealt rather skillfully with the aftermath: Large protests were allowed to take place, and Mr. Putin cleverly appointed a well-known human rights advocate, Ella Pamfilova, to lead the Central Election Commission. (She has not disappointed him.)

So why might Mr. Putin and his helpers be losing their touch now? Why would they overreact to the danger of a small beachhead of liberal activists on the Moscow City Council? Ask knowledgeable Russians this question, and you are likely to hear about the politics of succession. Under Russia’s Constitution, the president cannot run again when his term expires in 2024, but even that distant prospect has rattled the elite. Polls show public confidence in him has declined. His party, United Russia, is so unpopular that it lost a number of gubernatorial elections last year, and many of its candidates in local races are choosing to run as independents. The economy continues to stagnate. In this environment, some analysts say, Russian officials at all levels are asking whether Mr. Putin can guarantee institutional and social stability — and their personal safety — as he once did. If he can’t, making sure elections look free and fair may begin to look like a luxury that the regime can no longer afford.