Former world chess champion and vocal Kremlin critic Garry Kasparov is vying for the presidency of the World Chess Federation, or FIDE, against the Kremlin-backed incumbent, Kirsan Ilyumzhinov.
The sport's top job will be decided on August 11 in a secret vote by FIDE members in the Norwegian town of Tromsoe.
The campaign has been marred by allegations of vote-buying. Several national chess federations say they have been contacted by Russian embassies seeking to drum up support for Ilyumzhinov.
Kasparov, who retired from competitive chess in 2005, is a Russian opposition activist who once described President Vladimir Putin's government as a "dictatorship."
Ilyumzhinov is a former head of Russia's Kalmykia Republic, who claims he was once abducted by aliens.
Ilyumzhinov, who has presided over FIDE for 19 years, has been criticized for his close ties to dictators like Saddam Hussein and Muammar Qaddafi.
With reporting by AFP