OTTAWA -- Clayton Haluza was sitting at his desk on Bay Street when he learned the Liberal MP he spent countless hours campaigning for had defected -- a choice leaving him, and his party, blindsided a year out from an election.

Haluza, the president of the Aurora-Oak Ridges-Richmond Hill Liberal riding association, said he spent a good five minutes on Monday staring at the wall thinking, "what the heck has just happened?" when he read an update on his phone indicating that Leona Alleslev joined the Conservatives.

"There are no words to describe it," he said Tuesday in an interview, adding he did not receive a heads up.

"We had worked together since before she became a member of Parliament. We had a great working relationship."

Alleslev shocked political observers on the first day of the fall sitting by emerging on Parliament Hill with Conservative Leader Andrew Scheer, where he named her party critic for global security.

Alleslev, elected in 2015 for the Toronto-area riding, said she made the choice after questions about the Liberal government's approach on files including the economy, trade and defence were met with silence.

"At this time in our country's history we need strong leadership under the Conservatives and Andrew Scheer," she said Monday.

Haluza said Alleslev's decision is one he and countless Liberal volunteers are struggling to understand, especially after they gathered more than 100 signatures in the spring to ensure she could fly the Liberal flag in 2019.

"The reaction I've gotten from our membership base has been just one of hurt, anger, (and) displeasure, and from the community it's 'I voted for a Liberal,"' he said.

For her part, Democratic Institutions Minister Karina Gould maintained a poker face Tuesday when asked whether it feeds political cynicism when MPs switch parties.

"People have the right to change their opinions," she said in French, adding citizens will have their say during the election.

Haluza agrees voters will be able to weigh in on Alleslev's choice, noting his riding association is now focused on finding a replacement candidate to challenge Alleslev.

"A year from now the voters get the decision of whether they want her to still represent the riding," he said.

"I know that my team and I will be out there knocking on doors, convincing them that our party is still the right decision."