The debate over marijuana use in Canada has emerged in the federal election, pitting Liberal Leader Justin Trudeau squarely against Conservative Leader Stephen Harper over legalization.

Earlier this week, Trudeau stirred controversy when he vowed to legalize cannabis if elected. A day after clashing with Trudeau over the matter at the French-language debate, Harper challenged his opponent's stance again, and said marijuana is "infinitely worse" than tobacco.

The Conservatives are staunchly opposed to legalizing marijuana in Canada. Harper has said that it would do nothing to keep the drug away from children.

"We have spent a couple of generations trying to reduce the usage of tobacco in Canada with a lot of success," Harper said at a rally Saturday. "Tobacco is a product that does a lot of damage – marijuana is infinitely worse and is something we do not want to encourage."

Cannabis in Canada is already legal for those who use it for medical reasons, but if a Liberal government is formed, Trudeau has vowed to legalize recreational use, which he said would "remove the criminal element" linked to the drug and make it more difficult for youth to access.

Trudeau, however, has not said how his party would tax the recreational sale of marijuana, or how the drug would be controlled. However, behind the scenes, Liberals are already working on a plan.

CTV News has learned that Liberal candidate and former Toronto police chief Bill Blair is leading a team that will research best practices involving the possible legalization of marijuana in Canada.

"We've got good frameworks already in place," Blair told CTV News on Saturday. "We've already had a great deal of experience with controlling the sale and use of alcohol. We believe that we can build upon that model and we can ensure our communities could be made safer through regulation and legalization."

If pot becomes legal in Canada, it's still unclear how the Canadian economy would profit from the legal sale of pot.

The Liberals have not included marijuana sales in their costed platform so it's uncertain if a potential tax revenue would eventually help balance their bottom line.

But if Colorado's initial success with marijuana legalization is an indication, the Canadian economy could see a significant injection of green from the regulation of marijuana.

Last year, Colorado became the first U.S. state to legalize recreational pot-use. Since then, cannabis sale has generated $700 million in revenue in one year.

Meanwhile, the NDP said it supports the personal use of marijuana, but says more study needs to be done.

NDP Leader Thomas Mulcair has said, in the past, that he supports decriminalizing marijuana. However, he has not committed to legalizing it.

With a report from Deputy Ottawa Bureau Chief Laurie Graham