The new amendments to the law on political parties set the minimum number of party members at 50,000 and stipulate that parties which fail to comply must be transformed into public movements or closed down.
"Checks conducted by the Federal Registration Service in 2006 have revealed that 19 political parties meet the federal law requirements, but two of them - the Russian Party of Life and the Russian Party of Pensioners - have decided to turn into public organizations," said Galina Fokina, acting head of the political parties department in the service.
Russia's major parties, that managed to cross the 5% barrier needed to enter the State Duma in December 2003, presently include the ruling pro-Kremlin party United Russia, the nationalist Rodina (Motherland), the Communists and the ultra-nationalist LDPR.
Two right-wing parties - the Union of Right Forces (SPS) and Yabloko - failed to make it into parliament and have since been in talks to run for parliament as a single bloc, without reaching any agreement so far.
Irina Khakamada, a right-wing leader, and Russia's former Prime Minister Mikhail Kasyanov, a Yeltsin-backed figure, formed the People's Democratic Union movement in April. The organization was denied registration in October for failing to meet legal requirements. The movement described the decision as politically motivated.
Chess-champion-turned-politician Garry Kasparov formed the liberal United Civil Front movement in June but it has not been registered either for falling short of new membership standards.
In view of the fresh elections, the Party of Life, Pensioners and Rodina merged in October into the Just Russia party, which describes itself as a new leftist political force. Experts dismiss the party as another Kremlin project designed to poach votes from left-wing political forces.
Russia's election legislation has been subject to other amendments since the previous elections, which have been vehemently criticized by rights groups.
Lawmakers have abolished the 20% threshold for voter turnout, and canceled early voting and the "against all candidates" option on election ballots at all levels. The Kremlin has said these changes are needed to safeguard the development of Russian democracy from irresponsible marginal parties.
The threshold for parties seeking seats in the State Duma has also been increased from 5% to 7% in a move "to encourage parties to work harder and unite," as the top election official, Alexander Veshnyakov, has put it.
