 While still a Republican, Marks made an unsuccessful run for Congress in 1982 to unseat Phil Burton, losing by a margin of 58%-40%.Burton died unexpectedly of an aneurysm five months after the election at the age of 56 and was succeeded by Sala Burton, who would serve in the seat until her death less than four years later when she was succeeded by Nancy Pelosi, a longtime Burton family friend.He served in the Senate as a Republican until 1988, when he won re-election as a Democrat.