Voters across Russia cast ballots Saturday on the second day of an election set to formalize six more years of power for President Vladimir Putin, who faces no serious challengers after crushing political dissent over his nearly quarter-century of rule.

The election comes against the backdrop of a ruthless crackdown that has stifled independent media and prominent rights groups. Putin’s fiercest foe, Alexey Navalny, died in an Arctic prison in February, and other critics are either in jail or in exile.

The 71-year-old Putin faces three token rivals from Kremlin-friendly parties who have refrained from any criticism of him or his full-scale invasion of Ukraine. Putin has cast his war in Ukraine, now in its third year, as an existential battle against the United States and other Western powers bent on destroying Russia.

Officials said voting was proceeding in an orderly fashion. But despite tight controls, at least a half-dozen cases of vandalism at polling stations were reported Friday and Saturday, including a firebombing and several people pouring green liquid into ballot boxes. The latter was an apparent homage to Navalny, who in 2017 was attacked by an assailant who splashed green disinfectant in his face.

A 50-year-old university professor was arrested Saturday after she unsuccessfully tried to throw green liquid into a ballot box in the Urals city of Ekaterinburg. She was imprisoned for 15 days for “petty hooliganism,” but could face further charges, according to local news outlet Ura.ru.

A pensioner in the Altai region in southern Siberia was also detained after attempting to damage ballots, Russia’s state news agency Tass reported.

Russian lawmakers suggested introducing a law to punish election saboteurs with sentences of up to eight years in prison.

Meanwhile, a video released on social media by Russian election monitoring group Golos appeared to show staff at a polling station in the southern city of Krasnodar stuffing multiple voting slips into ballot boxes.

In the period leading up to the vote, Putin boasted about battlefield successes in Ukraine, where Russian troops have recently made incremental gains relying on their edge in firepower.

On Friday, Putin described cross-border shelling and incursions by Ukrainian forces during the past week as an attempt by Ukraine to frighten Russians and derail the vote. He vowed that the attacks “won’t be left unpunished.”

Analysts say the Kremlin needs a high turnout in the election to signal that Russians approve of the war and to legitimize Putin for another term.

The Russian defense ministry has served as a key growth engine, working around the clock to churn out missiles, tanks and ammunition and cushioning Russians from the economic impact of the war — driving down unemployment and driving up wages. Russia’s wartime economy has also proven to be resilient, expanding despite bruising Western sanctions.

Russia’s opposition movement has urged those unhappy with Putin or the war to show up at the polls at noon Sunday, the final day of voting, as a form of protest. The strategy was endorsed by Navalny not long before his death.

Voting is taking place at polling stations across Russia’s 11 time zones, in illegally annexed regions of Ukraine, and online.

Western leaders have derided the vote as a travesty of democracy.

European Council President Charles Michel mockingly congratulated Putin on Friday on “his landslide victory” in an election that was technically still underway. “No opposition. No freedom. No choice,” he wrote on the social media platform X.

Beyond the lack of options for voters, the possibilities for independent monitoring are very limited. No significant international observers were present. Only registered, Kremlin-approved candidates — or state-backed advisory bodies — can assign observers to polling stations, decreasing the likelihood of independent watchdogs.