Russian opposition democrats say who'll confront Medvedev
Nemtsov was supported by 114 delegates, with 23 votes against.
“We must propose an alternative to the current way of development. We think it should be the rule of law in Russia, provision of constitutional rights for all and a socially oriented market economy like in Europe,” Nemtsov said.
The party failed to reach the 7 % threshold to get into Russia's lower house of Parliament in December's election.
Nemtsov was the Deputy Prime Minister of the Russian Federation in 1998.
Former Prime Minister of Russia, Mikhail Kasyanov and Soviet era dissident, Vladimir Bukovsky, who also intend to run, joined the Congress as guests.