A day after an at-times heated debate on the economy, Tom Mulcair and Justin Trudeau were criticizing Stephen Harper for his use of the phrase “old stock Canadians” during an exchange on refugee policy.

During a major party leaders’ debate on the economy Thursday night, Harper came under fire on social media when he responded to a suggestion that Conservative policy strips refugees of some health care benefits.

Harper defended his party saying, “We do not offer them a better health plan than the ordinary Canadian can receive. That’s something new and existing and old stock Canadians agree with.”

At a campaign appearance in Calgary Friday morning, a reporter asked Harper what he meant by the phrase.

After reiterating his party’s stance on health care for refugees, Harper said, “It’s supported by Canadians who are themselves immigrants, and also supported by the rest of us – by Canadians who have been the descendants of immigrants for one or more generations.”

The claws quickly came out on social media when Harper initially made the remark, with many expressing displeasure – and confusion -- with the Conservative leader’s apparent categorization of Canadian citizens.

On Friday, Justin Trudeau’s campaign team said the Liberal leader didn’t respond to the “old stock” remark during the debate because he didn’t hear it.

But at a rally in Montreal Friday afternoon, Trudeau said the comment showed that Harper was “eager to use the politics of division” during the election campaign.

“The fact is, Mr. Harper is yet again highlighting that he doesn’t believe that a Canadian is a Canadian is a Canadian,” Trudeau said.

Mulcair also weighed in on the matter at a campaign stop in Regina Friday afternoon, saying Harper used “very divisive” language.

“I think we’re all Canadians and I don’t like dividing people into categories like that,” Mulcair said.

Social media takes notice

Twitter activity spiked Thursday night following Harper’s comments:

Post-debate, Google Canada also reported an increase in searches for “Old Stock Canadians.”