"Dear Friend," begins the six-page letter sent to Mr Churkin, asking for up to $US5,000 ($A7,095) to defeat Senator Barack Obama and help Senator McCain "promote freedom and democracy throughout the world", according to a copy of the letter provided to The Associated Press by the Russian mission.

Senator McCain has proposed expelling Russia from the Group of Eight world's major industrial nations and says Russia deserves international condemnation for its August war with Georgia.

He also has derided President George Bush for once saying he got a sense of Russian leader Vladimir Putin's soul the first time they met and locked eyes in 2001.

"I looked in Putin's eyes. I saw three letters: a K, a G and a B," Senator McCain said last year, referring to Putin's time in the Soviet Union's KGB security agency.

That approach has angered Moscow. Last month in New York, Russia's Foreign Minister, Sergei Lavrov, cast Senator McCain's foreign policy adviser, Henry Kissinger, as essentially clueless about the history behind the Georgian conflict.