Russia's protest movement against Vladimir Putin on Saturday hopes to rally tens of thousands for a new demonstration that is a test of their strength and tactics after his crushing election victory.
The opposition movement mustered huge numbers of around 100,000 for rallies after parliamentary polls in December but now must keep their momentum after Putin won a six year term as president in the March 4 elections.
Activists said there was massive fraud in the elections and complained their conduct was an "insult to civil society". But the protest movement also still needs to formulate a cohesive programme and overcome glaring divisions.
The Moscow city hall has approved a demonstration of up to 50,000 people on an avenue around the central Arbat area but so far less than 6,400 have said they are going on Facebook, far fewer than in previous actions.
"We need to move on to a programme for the future and stop shouting about the past," television host and journalist Ksenia Sobchak, who is expected to be one of the speakers at the rally, wrote on Twitter.
Police were highly visible in Moscow Saturday morning, lurking in buses parked around the city after the last rally on March 5 ended in mass arrests when some protestors refused to leave the venue.
According to Moscow police, some 2,500 members of the security forces will be on duty at the rally.
Activists have said the rally will focus on violations in the presidential polls which according to independent monitoring group League of Voters "discredited the Russian presidency, the electoral system and the whole state."
"The main slogans of the meeting are going to be 'For honest elections', 'For honest authorities' and 'Putin is not our president'" radical leftist leader Sergei Udaltsov told the Interfax news agency.
After holding four mass protests over the last three months and successfully breaking the taboo against opposition rallies in Russia, the movement now faces a huge challenge to decide where to go from Moscow.
"We need to be honest with ourselves," wrote Andrei Kolesenikov, commentator of the anti-Kremlin Novaya Gazeta newspaper.
"Changes are not going to be swift and will need long and hard political work, including the creation of new parties that are competitive even if the elections are rigged," he said.
The involvement of nationalist leaders and the sometimes inflammatory rhetoric of one of the most charismatic of the opposition leaders -- the anti-corruption crusader Alexei Navalny -- has also discomforted some liberals.
"For the first time in months, I am having doubts about whether to go to the next protest," Memorial human rights group head Oleg Orlov wrote on a blog for the Moscow Echo radio.
"Why is it that at every meeting I and my friends have to listen to radical nationalists?" Orlov asked.
The protest comes a day after US President Barack Obama telephoned Putin to congratulate him on his election victory, in a call that came several days after other world leaders but underlined the importance of the relationship.
The controversy over elections and the demonstrations has on occasion tested US-Russia relations, with Putin accusing Washington of funding NGOs with the aim of questioning the polls and sparking protests.
Putin, currently prime minister, won 63.6% of the vote in the elections and is now preparing for a May inauguration to take back the Kremlin job he held from 2000-2008 from his protege Dmitry Medvedev.