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 ā€œold stock Canadiansā€ during an exchange on refugee policy.

During a major party leadersā€™ 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, ā€œWe do not offer them a better health plan than the ordinary Canadian can receive. Thatā€™s something new and existing and old stock Canadians agree with.ā€

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

After reiterating his partyā€™s stance on health care for refugees, Harper said, ā€œItā€™s supported by Canadians who are themselves immigrants, and also supported by the rest of us ā€“ by Canadians who have been the descendants of immigrants for one or more generations.ā€

The claws quickly came out on social media when Harper initially made the remark, with many expressing displeasure ā€“ and confusion -- with the Conservative leaderā€™s apparent categorization of Canadian citizens.

On Friday, Justin Trudeauā€™s campaign team said the Liberal leader didnā€™t respond to the ā€œold stockā€ remark during the debate because he didnā€™t hear it.

But at a rally in Montreal Friday afternoon, Trudeau said the comment showed that Harper was ā€œeager to use the politics of divisionā€ during the election campaign.

ā€œThe fact is, Mr. Harper is yet again highlighting that he doesnā€™t believe that a Canadian is a Canadian is a Canadian,ā€ Trudeau said.

Mulcair also weighed in on the matter at a campaign stop in Regina Friday afternoon, saying Harper used ā€œvery divisiveā€ language.

ā€œI think weā€™re all Canadians and I donā€™t like dividing people into categories like that,ā€ Mulcair said.

Social media takes notice

Twitter activity spiked Thursday night following Harperā€™s comments:

Post-debate, Google Canada also reported an increase in searches for ā€œOld Stock Canadians.ā€