Russians crowded outside polling stations Sunday on the last day of a presidential election, apparently heeding an opposition call to protest against President Putin in a vote that offered them no real alternatives.

Mr. Putin is poised to extend his nearly quarter century of rule for six more years after a relentless crackdown on dissent — and early returns announced after polls closed in Russia showed he had nearly 88% of the vote with 24% of the precincts counted, according to Russia’s Central Election Commission.

The election took place amid attacks within Russia by Ukrainian missiles and drones, which have killed several people. Polling happened in a tightly controlled environment where Mr. Putin only faces competition from three token rivals and any public criticism of him or his war in Ukraine is stifled.

Mr. Putin’s fiercest political foe, Alexei Navalny, died in an Arctic prison last month, and other critics are either in jail or in exile. Beyond the fact that voters have virtually no choice, independent monitoring of the election is extremely limited.

Navalny’s associates urged those unhappy with Mr. Putin or the war to protest by coming to the polls at noon on Sunday — and lines outside a number of polling stations both inside Russia and at its embassies around the world appeared to swell at that time.

Among those heeding the call was Yulia Navalnaya, Navalny’s widow, who joined a long line at the Russian Embassy in Berlin as some in the crowd applauded and chanted her name. She spent more than five hours in the line and told reporters after casting her vote that she wrote her late husband’s name on the ballot.

Asked whether she had a message for Mr. Putin, Ms. Navalnaya replied: “Please stop asking for messages from me or from somebody for Mr. Putin. There could be no negotiations and nothing with Mr. Putin, because he’s a killer, he’s a gangster.”

Some Russians waiting to vote in Moscow and St. Petersburg told the Associated Press that they were taking part in the protest, but it wasn’t possible to confirm whether all of those pictured in line were doing so.

Joining a line at a polling station around noon in Moscow, a woman who said her name was Yulia told the AP that she was voting for the first time.

“Even if my vote doesn’t change anything, my conscience will be clear … for the future that I want to see for our country,” she said. She, like others, didn’t give her full name because of security concerns.

Another Moscow voter, who also identified himself only by his first name, Vadim, said he hoped for change, but added that “unfortunately, it’s unlikely.”

Independent Russian media posted images of spoiled ballots posted by voters, with “killer and thief” inscribed on one, and “waiting for you in The Hague” written on another, in a reference to an arrest warrant issued for Mr. Putin on war crimes charges related to his alleged responsibility for the abductions of children from Ukraine.

Still, some people told the AP that they were happy to vote for Mr. Putin. Dmitry Sergienko, who cast his ballot in Moscow, said, “I am happy with everything and want everything to continue as it is now.”

Voting took place over three days at polling stations across the vast country’s 11 time zones, in illegally annexed regions of Ukraine and online. While polls closed Sunday night in Russia, voting continued at some embassies around the world.

Despite tight controls, several dozen cases of vandalism at polling stations were reported across the voting period.

Several people were arrested, including in Moscow and St. Petersburg, after they tried to start fires or set off explosives at polling stations while others were detained for throwing green antiseptic or ink into ballot boxes.

Dmitry Medvedev, a deputy head of the Russian Security Council chaired by Mr. Putin, called for toughening the punishment for those who vandalize polling stations, arguing they should face treason charges.

Stanislav Andreychuk, co-chair of the Golos independent election watchdog, said that pressure on voters from law enforcement had reached unprecedented levels. Russians, he said in a social media post, were searched at polling stations, their ballots checked before they were cast, and police demanded a ballot box be opened to remove a ballot.

“It’s the first time in my life that I’ve seen such absurdities,” Mr. Andreychuk wrote on the messaging app Telegram, adding that he started monitoring elections in Russia 20 years ago.

A video, shared on social media, also appeared to show an armed man in camouflage gear going into booths, harassing Russians as they voted.

Ivan Zhdanov, the head of Navalny’s Anti-Corruption Foundation, said that the opposition’s call to protest had been successful. “The action has shown that there’s another Russia, there are people who stand against Putin.”

Huge lines also formed around noon outside Russian diplomatic missions in London, Berlin, Paris, Milan, Belgrade and other cities with large Russian communities, many of whom left Russia after Mr. Putin’s invasion of Ukraine.

Protesters in Berlin displayed a figure of Mr. Putin bathing in a bath of blood with the Ukrainian flag on the side, alongside shredded ballots in ballot boxes.

Russian state television and officials said the lines abroad showed strong turnout. The Russian Embassy in Germany posted a video of the queue in Berlin on X, formerly Twitter, with the caption, “together we are strong — Vote for Russia!”