THE WORLD - A new revolution urged in Russia - Opposition groups hope to defeat Putin's pick in next year's presidential election. Authorities appear to be on edge.

MOSCOW — Former world chess champion Garry Kasparov, now an opposition leader engaged in a high-stakes political match with Russian President Vladimir V. Putin, gamely put the best face on a modest turnout at a recent protest rally.

"There could have been many more people here if the authorities did not oppress people so much," Kasparov told a crowd of about 1,500 at the mid-June rally in a downtown Moscow park. "The authorities feel instinctively that if they allow people to march, there will be 1,000, then 10,000, then 20,000, and then everyone will come to the street."

City officials had refused permission for a march to follow the rally, and there were more police in attendance than protesters. In April, police arrested hundreds of demonstrators from the same coalition, Other Russia, when they sought to stage an unauthorized march.

Kasparov and his allies appear at times to be trying to trigger what some have lightheartedly dubbed a "White Knight" revolution -- a democratic ousting of the incumbent power structure following in the footsteps of Georgia's 2003 Rose Revolution and Ukraine's 2004 Orange Revolution.

The chess master and others say they are aiming at nothing less than winning the presidential election in March 2008.

Putin consistently enjoys popularity ratings above 70%, but the Constitution requires him to step down next spring at the end of his second term. Most observers believe that voters, heavily influenced by state-controlled television, will endorse whomever Putin selects as his preferred successor.

Likely contenders

The two contenders seen as most likely to win the Kremlin's nod are First Deputy Prime Ministers Dmitry Medvedev and Sergei B. Ivanov, who after many months of favorable coverage on state-controlled TV are now the country's most popular politicians after Putin.

The most visible potential opposition candidate is former Prime Minister Mikhail M. Kasyanov, who served during Putin's first term. He turned against his former boss after being dismissed shortly before Putin's 2004 reelection and now heads the People's Democratic Union.

Kasyanov, a founding leader of Other Russia, said Monday that the coalition had "fulfilled its mission," and implied that he was pulling out of it. The move appeared to mark a bid for top leadership of an even broader opposition coalition that would choose him as its candidate.