OTTAWA — A former top aide to Stephen Harper says Marilyn Gladu’s decision to leave the Conservative party for the Liberals weakens Pierre Poilievre’s leadership.

Dimitri Soudas, who was Stephen Harper’s director of communications, says Gladu was a “true blue conservative” and her decision to leave caught people off guard.

Gladu, who was elected as a Conservative MP four times, joined Prime Minister Mark Carney’s Liberals on Wednesday, saying the country needs a “serious leader.”

She’s the fourth Tory to defect since November and her flight to the Liberal bench puts the government in a position to secure a majority with three byelections set for Monday.

Conservative strategist Jeff Rutledge says Poilievre now needs to convey a message of confidence to his caucus and show that he has a plan.

The Conservative leader won the support of 87 per cent of delegates at the party’s convention at the end of January.

This report by The Canadian Press was first published April 9, 2026.

Sarah Ritchie and Catherine Morrison, The Canadian Press