"We need to see what will happen during the vote on his candidacy ... We see that as a certain sign of the fact that Washington attaches great importance to the situation in its relations with Moscow. The situation is very difficult. We hope that in case of his appointment here Sullivan will conduct a policy that will help to improve the current extremely difficult state of our relations", Ryabkov told reporters on the sidelines of the Moscow Nonproliferation Conference.
The Russian diplomat added that he had a "very pleasant" impression of Sullivan, whom he had met previously.
"He is a very experienced and knowledgeable person, a talented diplomat. Besides, he has a background of working in law firms and various important agencies of previous US administrations, which is as a whole a unique experience that, I hope, will help him to productively work in Moscow, if and when he is appointed", Ryabkov said.
Sullivan pledged late in October to support dialogue with Russia on arms control, terrorism fight, denuclearisation of the Korean Peninsula, and conflicts in Syria and Afghanistan.
US President Donald Trump announced on 11 October his decision to nominate Sullivan, currently serving as deputy secretary of state, as the new US ambassador to Russia. If the Senate approves his nomination, Sullivan will replace Jon Huntsman, who completed his tenure in Moscow on 3 October.
Earlier in his career, Sullivan served as Deputy Secretary of Commerce and held senior positions at the Departments of Justice, Defense, and Commerce, State Department said.
He has also advised the Attorney General, the Secretary of Defence, the Secretary of Commerce, and the Counsel to the President on legal and policy issues.
Before joining the government, Sullivan had more than 20 years of experience in private law practice.