Long lines of voters formed outside polling stations in major Russian cities during the presidential election on Sunday, in what opposition figures portrayed as a striking protest against a rubber-stamp process that is certain to keep Vladimir V. Putin in power.

Before he died last month, the Russian opposition leader Aleksei A. Navalny had called on supporters to go to polling stations at midday on Sunday, the last day of the three-day vote, to express dissatisfaction with Mr. Putin, who is set to win his fifth presidential term in a vote that lacks real competition.

Mr. Navalny’s team, which is continuing his work, and other opposition movements, reiterated calls for the protest in the weeks leading up to the vote. Simply appearing at the polling station, for an initiative known as Noon Against Putin, they said, was the only safe way to express discontent in a country that has drastically escalated repression since its full-scale invasion of Ukraine two years ago.

The opposition leaders said showing solidarity with like-minded citizens by mere presence was more important than what the voters chose to do with their ballots, because the election lacked real choice.

“This is our protest — we don’t have any other options,” said Lena, 61, who came to a polling station in central Moscow before noon with the intention of spoiling her ballot. “All of us decent people are hostages here.” Like other voters interviewed, she declined to provide her last name, for fear of reprisal.

Alissa, 25, said she came because she is against the war. “It is so important to see people who think like you, who don’t agree with what is happening,” she said.