* Fractured opposition faces uphill battle
* Sets sights on elections in 2011 and 2012
By Steve Gutterman
MOSCOW, Sept 16 (Reuters) - Four prominent government critics pushed to the margins of Russian politics during Vladimir Putin's presidency joined forces on Thursday for an uphill battle against the Kremlin in elections in 2011 and 2012.
Striving to turn a fractured opposition into a significant political force, Putin's former Prime Minister Mikhail Kasyanov teamed up with Boris Nemtsov and two other liberal politicians in a coalition they hope will attract other Kremlin opponents.
"Our main strategic goal is to change the political course of the country, and to achieve this it's necessary to change the leadership, whose course we view as fatal," Kasyanov said at a news conference announcing the coalition.
The politicians said they planned to form a party to compete in late 2011 parliamentary elections and field a candidate in the March 2012 presidential vote, in which Putin is expected to run himself or endorse incumbent Dmitry Medvedev.
Any opposition hopeful will have little chance against the Kremlin's candidate, but coalition leaders suggested they would use the campaign to rally popular support against entrenched leaders who have hinted they hope to rule for years to come.
"The agenda is the general democratisation of the political system, the restoration of civil rights and freedoms," said Vladimir Milov, a deputy energy minister during Boris Yeltsin's presidency in the 1990s.
He said the coalition would aim to create "a critical mass for change."
Critics of Putin, president from 2000-2008 and now prime minister, say he rolled back democracy after succeeding Yeltsin.
They point to the abolition of popular elections of regional governors and raised vote thresholds in legislative elections, which helped push liberals out of parliament and strengthen the Kremlin's domination of politics nationwide.
Nemtsov has taken to the streets, participating in frequent protests, and was arrested twice in August at demonstrations
The coalition leaders say the Kremlin has used dirty tricks, bureaucratic hurdles and state media to marginalise them in recent years, denying their parties registration required to participate in elections.
Liberal politician Vladimir Ryzhkov, a parliament deputy from 1993 to 2007 and one of the last independents in the national legislature, said the coalition would seek to register a political party by mid-2011, ahead of the parliamentary vote.
"If we are not registered, we will take steps to discredit the imitation elections," Ryzhkov said on Ekho Moskvy radio. (Additional reporting by Denis Dyomkin; Editing by Charles Dick)
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