Mikhail Prokhorov, the ex-head of the Right Cause party who quit the post last week, failed to show up at the party congress on Tuesday despite rumors about his possible reinstatement.
The billionaire ex-businessman was seen neither among delegates nor in the presidium.
The party split last Wednesday after Prokhorov and his supporters accused some members of illegally registering new members in his absence to win a majority and vote against his leadership.
The split came to a head last Thursday when two Right Cause parties - Prokhorov's opponents and supporters - met in different buildings in Moscow for their congresses in the run-up to the parliamentary elections in December.
The day before the congress resumed on Tuesday, Right Cause said in a statement it was in talks with Prokhorov about his possible reinstatement as party leader, but a spokesman for Prokhorov did not confirm the report.
