FACTBOX: 30 million Russians to vote in regional elections

MOSCOW (Reuters) - Russian President Dmitry Medvedev faces a test of his pledge to boost democracy on Sunday when polls open for 30 million voters in regional elections.

Here are some facts about the vote:

MOSCOW ELECTIONS

- More than five million voters are eligible to take part in elections to the Moscow city council, which has control over the city's $40-billion budget and veto power over Kremlin appointees to the post of mayor.

- Eighteen of the 35 seats in the Moscow council are distributed on a proportional basis among parties that secure more than 7 percent of the vote. The other 17 seats are elected on a first past the post basis.

REGIONAL ELECTIONS

- Regional, district and mayoral elections are taking place in 76 of Russia's 83 regions.

- Elections to regional assemblies in the Tula and Mari El regions near Moscow. Mayoral elections due in Chechnya's capital, Grozny, the far eastern city of Yuzhno-Sakhalinsk and Astrakhan on the Caspian Sea.

- First polls open in far eastern region of Kamchatka at 1900 GMT on Saturday. Exit polls due after final polling stations close at 1700 GMT on Sunday in the Western exclave of Kaliningrad.

PARTIES

- United Russia, the main pro-Kremlin party, is led by Prime Minister Vladimir Putin. (An October 2 Levada Center poll gave it 55.4 percent of the Moscow vote).

- The Communist Party is the biggest opposition force, but it rarely challenges the Kremlin on sensitive issues. (16.6 percent of Moscow vote in Levada Center poll).

- Liberal Democratic Party is a nationalist party that generally supports the Kremlin. (8.3 percent)

- Fair Russia is the second-largest pro-Kremlin party. (5.4 percent)

- Yabloko is the only pro-Western liberal party registered in the elections. Its rivals say it secured registration by showing support for the authorities. (2.8 percent)

- The Kremlin's fiercest critics are represented by political movements that have not been registered as parties, such as Solidarity, run by Boris Nemtsov and Garry Kasparov.

(Figures in brackets from a poll of 1,005 people in Moscow on October 2 by the Levada Center, the only major polling organization to question voters)

(Reporting by Conor Humphries; Editing by Janet Lawrence)