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 Russian 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 his death 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 protestors to spoil ballots by writing «Navalny» on them, or vote for candidates other than Putin.
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 told AFP he would take part in the protest at 12:00 pm (0900 GMT) in the capital, «just to see young supportive faces around… feel some support around me, and see the light in this dark tunnel.»
The man, who declined to give his name for security reasons, said he hoped the demonstration would show the authorities «that there are people in this country against the