MOSCOW (AP) — Russia's governing party and its three largely cooperative opponents are expected to retain their positions in the national parliament, but new procedures for choosing the seats could affect their proportions.

Voting for the State Duma began Sunday morning in the Far East, nine hours ahead of Moscow and won't conclude until 22 hours later when polls close in the Baltic Sea exclave of Kaliningrad.

There are 450 seats at stake in the Duma, but unlike the last two sessions, only half the seats are chosen by national party-list; the other 225 are contested in specific districts.

Nationwide polling in recent weeks have shown the pro-Kremlin United Russia with support of around 50 percent of likely voters, which would be enough to maintain its absolute majority.