Russia's former ambassador to the United States says "toxic" political infighting is preventing U.S. President Donald Trump from improving relations with Russia.

Ties between the two countries have been deteriorating steadily since Russia annexed the Crimean Peninsula and threw its weight behind separatists in eastern Ukraine. Moscow's hopes that President Trump would be willing to start the relationship from a clean slate have been largely disappointed.

Sergei Kislyak served as Russia's ambassador in Washington from 2008 until his tenure ended last year amid scrutiny of his recurrent meetings with the Trump campaign staff. He told The Associated Press on Friday that Trump appears eager to improve ties with Russia but the "toxic" political climate is making it impossible for him.