Max Sieben Baucus (born December 11, 1941) is an American politician who was a United States Senator from Montana from 1978 to 2014. A member of the Democratic Party, Baucus was the longest-serving U.S. senator from Montana. Baucus has been the United States Ambassador to China since 2014.As the Chairman of the Senate Committee on Finance, Baucus played an influential role in the debate over health care reform in the United States.