The carnival is over for Russia's three-month-old protest movement against Vladimir Putin.

Following his emphatic presidential election victory, the disparate group of artists, authors, bloggers and other members of the urban intelligentsia who have joined the few politicians in organising the protests are struggling to keep up the momentum as they prepare for a new protest on Saturday.

The festive atmosphere that swept tens of thousands into the streets of Moscow has gone after riot police detained hundreds of protesters on Monday. Many are looking for a new direction.

The romantic, euphoric phase is over: People have understood that armed with just white balloons and white ribbons ... you can't go up against robots from the OMON (riot police), said novelist Grigory Chkhartishvili, one of the organisers who writes under the name of Boris Akunin.

Now there will be some kind of public stupor.

The protest organisers, who made white ribbons the symbol of their protests, say Sunday's election was marred by fraud. But the margin of victory - the official count gave Putin almost 64 percent of votes - has taken the wind out of their sails.

Although they refuse to recognise the official tally, describing it as an insult to the Russian people, they have been forced to accept that Putin secured a majority, regardless of whether his victory was swollen by fraud.

Their task now is to find a way to keep the protesters united and to force Putin to listen.

Some say they will have to become more overtly political. Until now they have skirted around political questions because they could threaten the unity of a movement that brings together nationalists, leftists and independent groups as well as people who took little or no interest in politics until now.

We are going to keep coming out into the street, but we have to think of something more concrete, something other than protests, said Nikolai Belyaev, who was briefly detained after being caught up in a crowd of protesters who refused to go straight home after demonstrating in central Moscow on Monday.

A manager at a French chemicals firm in Moscow who saw himself until recently as apolitical, he has quit his job and thrown himself into the protest movement.

I very much want to hope that society is not going to fall asleep again. I see my personal goal as developing a civil awareness in others, he said.

The authorities have not yet realised that a new tradition of societal control over power is being born in Russia.

PUTIN TRIES TO RIDE IT OUT

The Kremlin has offered a few concessions since the protests began in anger at widespread reports of fraud in a parliamentary election on December 4 that was won by Putin's party, but has rejected their main demands such a rerunning the poll.

Its post-election strategy appears clear: Putin will allow a few isolated protests, agreed ahead of time with authorities, as a safety valve for disillusionment with his domination since rising to power in 2000.

The former KGB spy who has served as prime minister since 2008, when his first, eight-year spell as president ended, has made clear he thinks the protests will fade.

He has signalled he is ready to make conciliatory gestures, such as holding gubernatorial elections, reversing a policy under which the Kremlin appointed regional leaders, but these are widely seen as token moves that will take years to enact.

Many protesters are wondering how effective the protests can be as they prepare for Saturday's rally in central Moscow.

The fun is over, said Tikhon after Monday's protest. I'm mostly cold and tired. I'm going home.

The organisers say the protesters have to think of their movement as a marathon, not a short dash to victory.

Nothing happened that we did not expect, Alexei Navalny, an anti-corruption blogger who has emerged as the most charismatic of the protest organisers, said at a Moscow cafe where the opposition set up headquarters for the election.

This is not a sprint. We shouldn't be naive and think something grandiose, some kind of change will come in the next two to three weeks. Our task is to build up the protest movement.

That is not going to be easy because the Kremlin controls much of the media and the protests have been largely restricted to Moscow and St Petersburg, although there have been a few isolated protests in other big cities.

The problem isn't that the protests are ebbing ... but that the social base of the protest, which grew sharply in recent months, has reached a ceiling, said Yuri Saprykin, editor of the Rambler-Afisha media group that has helped organise rallies.

Putin did win. It is a scientific fact. Even taking all the falsifications into account, he wrote in an opinion column. Putin has a majority opposed by nothing, no-one. At least yet.

SPROUTING ROOTS

Sociologists and political analysts say that even if the protests ebb, the demands that have been voiced for more democracy, independent courts and transparency will continue to echo and chip away at Putin's credibility.

They may be a minority, they may be focused mainly in Moscow, but they remain an important factor that has eroded Putin's legitimacy and will lead to other changes, said Maria Lipman, an expert with the Moscow-based Carnegie Centre.

Bringing cases of electoral fraud to court is one means at the protesters' disposal.

Some of the organisers have also suggested focusing their battle more on changing the capital from the inside by contesting city elections in Moscow in 2013.

Twenty-year-old student Vera Kichanova, who protested against President Dmitry Medvedev's visit to her journalism school last year, has already won a district council seat.

Moscow is the only city where Putin does not have a solid majority, said journalist Sergei Parkhomenko, a protest organiser. In the near future, we must wage a peaceful fight for Moscow.

(Additional reporting by Gleb Bryanski, Editing by Timothy Heritage and Elizabeth Piper)