The parliamentary leader of the Our Home Is Russia party, Aleksander Shokhin, has quit after his group voted to dismiss him.
The head of the party, and former prime minister, Victor Chernomyrdin, had indicated his dissatisfaction with Mr Shokin's performance.
Mr Chernomyrdin is not a member of parliament so cannot lead his group of deputies.
Correspondents say Mr Shokhin, who had openly rebelled against Mr Chernomyrdin's leadership, was seeking new alliances for the party, and had supported closer links with the Mayor of Moscow, Yuri Luzhkov, and his political movement.
Mr Shokhin was replaced as parliamentary leader of Our Home Is Russia by Boris Kuznetsov.
From the newsroom of the BBC World Service