Canada's Conservative prime minister posed for pictures with Toronto's former crack smoking mayor and thanked his family for helping organize a campaign event ahead of Monday's election.

Prime Minister Stephen Harper, who has been in power for a decade, is trailing Liberal leader Justin Trudeau, the son of late Prime Minister Pierre Trudeau, in the polls.

Ex-Toronto Mayor Rob Ford's term as mayor was plagued by admitted crack cocaine use.

Doug Ford, his brother, made a speech before Harper spoke in the Toronto suburb of Etobicoke, where Ford remains popular.

Doug Ford, a former city councilor, has himself has been the subject of drug allegations. The Globe and Mail newspaper reported in 2013 that he sold hashish for several years in the 1980s, allegations he has denied.