U.S. Ambassador to the UN John Bolton resigned earlier Monday and will leave his post December 31 when his term expires.
"We would like to express the hope that his successor will be able to overcome an excessively tough approach and preserve and develop the positive experience of our cooperation," the Russian Foreign Ministry said.
The ministry said Bolton "has been a strong professional, although his approach was fairly tough in some issues, including UN reform."
Since taking office in August 2005, Bolton, known as an uncompromising and outspoken figure, has pushed for faster reform at the UN, including in the management structure and fund allocation.
"But we cooperated with him successfully on an entire range of problems," the ministry said.
Bush himself appointed Bolton his UN ambassador after the Senate refused to approve his candidacy, which is why he can only stay at this post until December 31.
The White House said earlier it would put forward Bolton's candidacy again before the Senate following midterm elections in November, but with a Democratic sweep of Congress any chance of winning approval was effectively lost.