[3] Swan first ran for the Manitoba legislature as a New Democrat in the 1990 provincial election,[4] placing third in the west-end Winnipeg riding of Sturgeon Creek.

On June 22, 2004, Swan was elected as a New Democrat for the riding of Minto, defeating his next closest competitor, Liberal Wayne Helgason, by 2,848 votes to 1,616.

[12] After winning the leadership race, Selinger appointed Swan as Minister of Justice and Attorney General on November 3.

Swan resigned his cabinet position on November 3, 2014, along with Jennifer Howard, Theresa Oswald, Erin Selby and Stan Struthers, due to concerns about Premier Selinger's leadership.

He did not seek re-election in the snap 2019 Manitoba general election, at which the 2018 electoral redistribution, which eliminated Minto, took effect.