Incumbent governor Arthur B. Langlie, a Republican who had served three terms, announced on May 2 that he would not run for a fourth term and instead challenge Warren Magnuson for one of the state's U.S. Senate seats. Langlie made no public endorsement for a Republican candidate, but privately supported congressman Thor C. Tollefson prior to the announcement. Tollefson would later drop out of the gubernatorial race by the end of the month and pursue another congressional term, leaving Lieutenant Governor Emmett T. Anderson and Attorney GeneralDon Eastvold as the remaining Republican frontrunners. Albert D. Rosellini, a Democratic state senator from South Seattle, announced his candidacy on May 24, proposing a state department of commerce, industrial regulations, diversification of jobs and industries, a second Lake Washington bridge, and toll-free superhighways. Rosellini, a New Deal liberal Democrat who had been named leader of the state's Democratic Senate Caucus, publicly opposed Langlie during his three terms as governors and often butted heads with the former Seattle mayor. After missteps during his 1952 bid for governor, Rosellini was left to run in the 1956 race using his own funds. State Secretary of StateEarl Coe, another Democrat, joined the race in early July and became Rosellini's biggest challenger for the Democratic nomination. By the filing deadline in July, the field of candidates grew to nine, with Democratic state senator Roderick A. Lindsay of Spokane joining the race. Prior to the primary, Anderson emerged as a Republican favorite among former Langlie supporters, while Democrats Coe and Rosellini were expected to split a contentious vote. During the September 11blanket primary, Rosellini and Anderson won the right to advance to the general election, with comfortable margins in early returns. Coe formally endorsed Rosellini on September 26, citing a preference to avoid "past stalemates" and encouraging voters to give majority control of the legislature to the Democrats.
was nominated by the Socialist Labor Party of Americain September and approved by the Secretary of State as the only minor party in the governor's race. Rosellini spent much of his campaigning proposing improvements to the state's institutions, including prisons and schools, while attacking the Langlie administration. Anderson, by contrast, made few promises and touted his qualifications as lieutenant governor. On November 6, Rosellini won the governorship and promised to promote bipartisanship and select state employees on merit rather than political qualifications. Anderson formally conceded to Rosellini the following morning, congratulating him on his victory and thanking his supporters.
