Two municipalities in Ontario are among the five federal ridings holding by-elections today.
Voters will head to the polls in Ottawa-Vanier and Markham-Thornhill, both ridings that were previously held by the governing Liberals.
John McCallum, the former immigration minister who was the MP for Markham-Thornhill, was named ambassador to China earlier this year.
And Mauril Belanger was the MP for Ottawa-Vanier for over 20 years before his death in 2016.