A Russian opposition group founded by the former world chess champion, Gary Kasparov, has been barred from taking part in December's parliamentary polls.
Mr Kasparov says he offers a viable alternative to Putin's Russia
Mr Kasparov was one of three candidates put forward by the Other Russia bloc.
In a widely expected move, all three were blocked by the election commission because the small Other Russia group is not registered as a political party.
Parties loyal to the popular President Vladimir Putin are expected to win the 2 December elections.
Other Russia has described new Russian laws governing the registration of political parties as discriminatory.
The group brings together a broad coalition of mainstream politicians, leftists and nationalists, all of whom are opposed to President Putin.
Mr Putin stands down when Russia elects a new president in March 2008, as the constitution bars him from seeking a third consecutive term.
He has said he plans to add his name to his party's list in December's parliamentary vote, which effectively guarantees him a seat in the next parliament.
He has also described as "entirely realistic" the suggestion that he may become the next prime minister of Russia.
Mr Kasparov has said he too will run for the presidency next year.
The election is expected to be won by the person Mr Putin nominates as his successor.