In 1963 Durkan became chairperson of the Subcommittee on Revenue and Regulatory Agencies. He drafted legislation allowing the Seattle Center Monorail of the 1962 World's Fair to be owned an operated by the state instead of the city, which Rosellini was against. He introduced a bill to remove tax exemption from cooperative apartment buildings for senior citizens. After reducing budgetary spending on funding for mentally handicapped people, he introduced legislation to close Northern State Hospital in Sedro-Woolley. He was the Western Washington campaign manager for President Lyndon B. Johnson's 1964 presidential campaign.