MOSCOW — Not even 24 hours after a judge ordered him handcuffed and imprisoned to begin a five-year sentence for embezzlement, the Russian political opposition leader, Alexei A. Navalny, walked free — temporarily, at least, pending an appeal.
It was a head-spinning turn that gave Navalny new grounds to challenge the authorities, thrilled his supporters — prematurely, perhaps, as he remains convicted of a serious crime — and set off speculation about the government’s motivations and goals in jailing and then freeing President Vladmir V. Putin’s chief antagonist.
His release was requested by the very same prosecutor who asked that he be locked up in the first place.
Supporters of Navalny insisted that an unsanctioned rally Thursday evening by thousands of people in Manezh Square near the Kremlin, blocking traffic and chanting “Freedom!” and “Navalny!” had forced officials to let him go. Other commentators and analysts said his release reflected disagreement and disarray at the highest levels of government.
The official reason given by prosecutors was Navalny’s recently declared candidacy for mayor of Moscow — a campaign that he and his aides said he would now be able to continue.
But if his conviction is not reversed on appeal, Navalny cannot hold public office, raising a possibility that he was freed to lend legitimacy to the race, with no real chance of him ever serving as mayor.
Sergei S. Sobyanin, the incumbent mayor who is heavily favored to win reelection in the Sept. 8 balloting, seemed to lend some credence to that theory Friday. Rather than quietly enjoying the downfall of a popular rival, Sobyanin said he favored Navalny’s participation, and that the court proceedings should not interfere.
“I think it would be wrong to remove any of the candidacies,” the silver-haired Sobyanin said in a television interview. “We have spent a lot of effort so that Muscovites had the right to a choice, the maximal choice, and to register among others, Navalny’s candidacy. So I consider it necessary to do everything so that all registered candidates continue to participate.”
Despite Sobyanin’s remarks, the inherent risk of giving Navalny a prominent platform in Moscow politics fueled rampant guessing about what other machinations may be at work.
One possibility was that the authorities were following a long pattern of slight backtracking in politically charged verdicts that can blunt criticism at home and abroad.