Rigg resigned from the legislature in 1917 to campaign for the Canadian House of Commons a second time. The SDP had initially nominated John Queen as its candidate in Winnipeg North, but the city's centrist labourites declared that Queen could not win and nominated Rigg in his place. Rigg's nomination was subsequently confirmed by special convention of Winnipeg's working-class organizations. He also received the endorsement of the "Laurier Liberals", who declined to offer a candidate of their own.
