United Russia has won half of the votes in Sunday’s parliamentary election.
Communists came in second with nineteen percent, followed by Fair Russia and the nationalist Liberal Democrats.
Such are the official results announced with 96 percent of the ballots counted.
This is a sharp drop in support for Vladimir Putin’s ruling party.
It deprives United Russia of the two thirds majority which it enjoyed in parliament and which allowed it to amend the constitution.
President Medvedev says the outcome reflects the situation in the country and testifies to democracy.
There has been popular discontent with the ruling party, seen as representing corrupt government.
Its three main competitors benefited from the protest vote, performing better than in the previous election.
Rival parties claim there was mass voter fraud.
The Yabloko and Right Cause parties which fell short of passing to the State Duma vow to contest the outcome.
International observers say the election lacked fair political competition and saw a convergence of the state and the governing party.
They registered breaches and manipulations during the vote count, including ballot box stuffing.
Many observers also complained their activities were obstructed.
The vote was considered crucial for Vladimir Putin ahead of the March presidential election.