The U.S. Democratic Party won Tuesday's congressional election, which gave it a majority in the House of Representatives, the lower house of the American Congress, while results for Senate races have yet to be finalized.
Sergei Rogov, director of the U.S. and Canada Institute of the Russian Academy of Sciences, said bilateral relations will continue deteriorating, as he saw no fundamental differences between Republicans and Democrats.
"Both of them extremely negatively evaluate Russia's domestic and foreign policies," Rogov said, commenting on the preliminary outcome of the elections.
He said the partnership announced five years ago "turned out to be only declarative."
"This partnership has no content today, and mutual claims against one another keep growing," the expert said.
Russia was one of the first nations to express solidarity with the U.S. after the devastating attacks on New York and Washington September 11, 2001.
But relations have since deteriorated for a variety of reasons, including Moscow's concerns over U.S. foreign policy in the former Soviet Union and anxiety in Washington over the Kremlin's alleged "backsliding" on democracy.
Rogov said the success of the Democrats in the elections was "a serious defeat for [President] George Bush, and the main reason for that was the war in Iraq."
"American society realizes that there will be no victory in Iraq, and that the war will end with a defeat [of the U.S.]," Rogov said. "That explains the result of the elections."
The war in Iraq is another stumbling block in bilateral relations between the two countries, as Russia has been consistently critical of the U.S.-led military campaign in a country with which it had extensive economic relations during the rule of Saddam Hussein.
The invasion began in March 2003 on the ostensible pretext of eliminating Iraq's weapons of mass destruction, which never materialized.
"It becomes obvious that the United States cannot play the role of the world's policeman," Rogov said. "We may expect a stage-by-stage withdrawal of U.S. troops [from Iraq] starting next year."