OTTAWA — A former top aide to Stephen Harper says Marilyn Gladu’s decision to leave the Conservative party for the Liberals is raising questions about Pierre Poilievre’s leadership.
“I think this floor crosser, more than the previous ones, weakens his leadership,” said Dimitri Soudas, who was former prime minister Stephen Harper’s director of communications.
“Not just because of the fact that it’s a fourth floor crosser, but that this was a true-blue conservative.”
Gladu, who was elected as a Conservative MP four times, joined Prime Minister Mark Carney’s Liberals on Wednesday.
She didn’t directly criticize Poilievre’s leadership but she said she was joining Carney’s team because the country needs “a serious leader.”
Her flight to the Liberal bench puts the government in a position to secure a majority by winning at least one of the three byelections set for Monday.
Gladu is the fourth Conservative to defect since late last year. A fifth opposition MP, Lori Idlout, crossed to the Liberals from the NDP.
The first of the floor crossers, Nova Scotia MP Chris d’Entremont, cited Poilievre’s leadership style as a factor in his decision to leave the caucus.
Ontario MP Michael Ma crossed the floor in December, and Alberta MP Matt Jeneroux switched sides in February. Rumours have swirled for months about more Conservatives considering crossing the floor.
Gladu, however, was not among those being discussed on Parliament Hill as potential future Liberals.
During her time in Ottawa, Gladu has railed against COVID-19 pandemic restrictions, apologized publicly for spreading vaccine misinformation, voted against a bill banning conversion therapy, and taken part in anti-abortion rallies.
NDP MP Leah Gazan called Gladu a “far-right social conservative” in a statement on Wednesday. Bloc Québécois Leader Yves-François Blanchet accused the Liberals of flirting with opponents who “are a bit intense about controlling women’s bodies.”
Amanda Galbraith, a former adviser to Harper and a partner at public affairs firm Oyster Group, said the MPs who have chosen to leave are not the core of the Conservative caucus.
“I think that is actually a good sign for caucus unity,” she said.
“But obviously, these things are challenging and political parties go through them.”
Galbraith said she thinks Poilievre’s leadership is safe and she hasn’t heard of anyone organizing against him.
Conservative strategist Jeff Rutledge said Poilievre needs to convey a message of confidence to his caucus — particularly since Gladu’s departure came a day after Poilievre’s director of communications, Katy Merrifield, said she was leaving her post.
“You can’t have all of these things happening and necessarily present the public image that everything is ticking along fine. And so that’s where the role of a leader is to communicate honestly about what’s going on, but also have a plan,” he said.
Poilievre’s hold on the leadership has been questioned several times since last year’s election, when he lost the Ottawa-area riding he held for more than 20 years to a Liberal.
The Tory leader was sidelined from the House of Commons last spring, but returned in the fall after winning a byelection in the Conservative heartland in Alberta.
For much of the past year, pundits have called for Poilievre to shift his tone and message as poll after poll showed he was personally unpopular with Canadians.
The questions seemed to be settled when Poilievre won the support of 87 per cent of delegates at the party’s convention at the end of January. The party said it was strongly united around his leadership.
“It’s easy to win the leadership of your party if you believe you’ve got the core base support,” Rutledge said.
“It’s a much more challenging thing to secure the support of your caucus, who have individual constituent issues to address, who have their own kind of goals and desires when it comes to politics.”
Galbraith said Poilievre’s recent efforts to present himself as a prime minister in waiting — through international trips and appearances on high-profile podcasts like “The Joe Rogan Experience” — have been “broadly well-received.”
“When you are the opposition leader … everybody’s an armchair quarterback around how you could do stuff differently,” she said.
Soudas said he expects to see more floor crossers.
“At some point I think Mr. Poilievre has to think hard as to whether or not he is the right person to lead this party into the next election and deliver a Conservative victory,” he said.
This report by The Canadian Press was first published April 9, 2026.
Sarah Ritchie and Catherine Morrison, The Canadian Press
