Russian opposition politician Alexei Navalny says he has gathered enough nominations to challenge Vladimir Putin in March’s presidential election.
His supporters met in 20 cities across the country to secure the signatures.
Mr Navalny is still unlikely to run as election officials ruled him ineligible because of a corruption conviction which he says is politically motivated.
Mr Navalny spoke at the Moscow gathering, branding Mr Putin a “bad president”.
He told his supporters in a marquee on a snowy riverbank that he would call a boycott of the election if he were not allowed to stand.
Mr Navalny is widely regarded as the only candidate with a chance of challenging the president, who is seeking a fourth term that would see him become the longest-serving Russian leader since Joseph Stalin.
Russian socialite and TV presenter Ksenia Sobchak is standing in the election but some – including Mr Navalny – regard her as a “Kremlin stooge”.
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Separately on Sunday, an opposition rally called by activist Ilya Yashin was held in the north-west of the capital.
Dozens attended the rally, which was streamed live on Facebook by Radio Liberty, chanting “Russia will be free” and “Putin is a thief”.
Police declared it “illegal and provocative” and vowed to act in “strict accordance with the law”. However, no-one was detained.