The campaign comes as pro-Ukrainian groups aim to sabotage the three-day vote such as through arson attacks.
Kremlin critics called for massive protests at Russian polling stations on Sunday for the final day of a presidential election that is guaranteed to cement Vladimir Putin’s hardline rule.
The three-day vote has already been marred by a surge in fatal Ukrainian bombardments and a series of incursions into Russia’s territory by pro-Ukrainian sabotage groups.
There have also been acts of protest in the first days of polling, with a spate of arrests of Russians accused of pouring dye into ballot boxes or arson attacks.
Before he died in an Arctic prison last month, opposition leader Alexei Navalny, who galvanised mass anti-Putin rallies, urged Russians to protest on Sunday.
His widow, Yulia Navalnaya, has reiterated his call in the run-up to the election and said protesters should show up in large numbers at the same time to overwhelm polling stations.
She called for protesters to spoil ballots by writing “Navalny” on them or vote for candidates other than Putin.
Fatal Ukrainian strikes rock Russia as vote cements Putin’s grip
Any public dissent in Russia has been harshly punished since the start of Moscow’s offensive in Ukraine on February 24, 2022, and there have been repeated warnings from the authorities against election protests.
A Moscow resident in his twenties said he would take part in the protest at noon (9 am GMT) in the capital “just to see young supportive faces around … feel some support around me, and see the light in this dark tunnel”.
