Prime Minister Mark Carney is sending voters to the polls in three ridings next month in a series of unusually important byelections.

Voters in Ontario’s Scarborough Southwest and University-Rosedale and Quebec’s Terrebonne will cast ballots on April 13, Carney announced on Sunday.

If the Liberals were to win all three votes, it will bring the government caucus up to 172 seats, the bare threshold for a majority in the House.

The two Ontario ridings, both located in Toronto, are seen as Liberal strongholds. The party won both ridings with over 60 per cent of the vote in last April’s election.

They both became vacant after their sitting MPs resigned for jobs overseas. Chrystia Freeland stepped down as the MP for University-Rosedale in January after she agreed to become the new head of the Rhodes Trust and to act as an advisor to Ukraine President Volodymyr Zelenskyy.

Bill Blair resigned as the MP for Scarborough Southwest to become Canada’s high commissioner to the United Kingdom.

The race in Terrebonne should be much closer.

Liberal candidate Tatiana Auguste won the riding by a single vote over Bloc Quebecois incumbent Nathalie Sinclair-Desgagné.

But the Supreme Court last month vacated the results after it was uncovered that Elections Canada failed to count a vote from a Bloc supporter.

It will be a rematch in Terrebonne, where Auguste will carry the Liberal banner and Sinclair-Desgagné will run for the Bloc.

In Scarborough Southwest, the Liberals are putting forward Doly Begum, who represented the provincial iteration of the riding for the Ontario NDP.

Begum resigned the provincial seat and as deputy leader of the Ontario NDP to jump to federal politics.

Danielle Martin, a prominent doctor and healthcare advocate, is running for the Liberals in University-Rosedale.

Even if the Liberals were to win all three seats, it still not be an easy path in the House.

The speaker is a Liberal and will only vote in the case of a tie. Based on convention, the speaker votes to continue debate, meaning they would back the government in a non-confidence matter.

But it becomes less clear what would happen on other matters. It could also stall Liberal efforts to use time allocation or closure to speed through the passage of major legislation.

As in previous byelections, iPolitics will have liveblog coverage of the votes on April 13.