Kremlin challenger Boris Nadezhdin says he has collected enough signatures to stand as a candidate in Russia's upcoming presidential election.
The former local councillor has become known for his relatively outspoken criticism of Mr Putin and of Russia's full-scale invasion of Ukraine.
Mr Nadezhdin said he handed over more than the 100,000 required signatures to the electoral authorities.
The electoral commission must now review his application.
Current president Vladimir Putin has already registered as an independent candidate for the election in March, which will almost certainly see him win another six-year term.
Mr Nadezhdin, 60, was a local councillor for more than 30 years. In a country where opposition figures have been jailed or even assassinated, his recent criticism of Mr Putin appears to have been tolerated so far.
He recently said the president had "practically destroyed the key institutions of the modern state of Russia", and told the OceanNewsUK that, if elected, his first task would be to end the war in Ukraine.
Shortly after today's deadline to hand in the signatures, Mr Nadezhdin posted a photo of himself standing in front of several boxes containing papers bearing the signatures of his supporters.
"This is my pride - the work of thousands of people over many sleepless days. The result of the queues you stood in in the freezing cold is in those boxes," he wrote on X, formerly Twitter.
Thousands of Russians have queued in the cold across the country to add their signature to the list of people supporting Mr Nadezhdin's bid.
Russia's political scene has been dominated by Vladimir Putin since 2000. In 2020, a constitutional amendment was passed allowing him to stay in power beyond 2024.
A victory in March would see him remain as president until 2030. After that, he can then potentially serve another six years until 2036 if he decides to stand again.
