Looking back on his time as prime minister, Justin Trudeau said that abandoning his promise of electoral reform was his biggest regret.

"Particularly as we approach this election … I do wish that we'd been able to change the way we elect our governments in this country, so that people could choose a second choice or a third choice on the same ballot," Trudeau said after announcing his resignation in January, seeming to support a ranked ballot that would let voters pick their preferred candidates…