An elected Liberal government would begin working to legalize and regulate marijuana "right away," Justin Trudeau says.

"The Liberal Party is committed to legalizing and regulating marijuana," Trudeau said, in response to a reporter's question in Surrey, B.C., on Wednesday.

The Liberal Party Leader declined to set a firm timeline for legalization, but vowed to make it an early priority if elected on Oct. 19.

He said legalizing marijuana would fix a "failed system" and help "remove the criminal element" linked to the drug.

Trudeau went on to accuse Conservative Leader Stephen Harper of implementing anti-marijuana policies that allow the drug to fund "criminal organizations, street gangs and gun-runners."

"It is our intention to stop Mr. Harper's failed approach on marijuana," Trudeau added.

Trudeau said legalization could happen anywhere from a month to "a year or two" into a Liberal government, but he would make sure the process gets underway shortly after taking power.

The Liberal Party's recently-released costing platform does not include a plan to regulate or tax marijuana.

Trudeau addressed that matter on Wednesday, saying that his party would want to look at best practices in other jurisdictions, before deciding on how best to regulate it in Canada.

"We believe in being responsible and realistic in the costing of our plans," Trudeau said. "We didn't book for tax revenues for marijuana because we don't yet know what rate we're going to be taxing it."

Trudeau has voiced his support for relaxing marijuana laws in the past, but he has largely stayed away from addressing the issue during the election campaign.

Harper has often criticized Trudeau for his pro-marijuana stance. Last month, he said most Canadians "do not want the full legalization of marijuana."

In an appearance on CTV News Channel, Conservative candidate Rona Ambrose said that legalizing marijuana is a "terrible idea" because it would signal to young Canadians that "it is normal and it is OK."

"When you legalize something, you normalize it," said Ambrose.

"And I worry about that because we have … very clear evidence that there are very serious health impacts on children – anyone under the age of 25."

The health minister also said that she was skeptical that the government can keep marijuana out of the hands of children.

"We know that our experience with alcohol says otherwise," said Ambrose.

She also repeated the oft-used claim that should the Liberal plan succeed, marijuana will be available for sale in corner stores.

However, on Sept. 2, Trudeau said he was not "comfortable" with the idea.

"At this point, I don't think corner stores necessarily are rigorous enough at checking ID to make me comfortable with that as an option," he said at the time.

Ambrose also said legalization could create a powerful lobby for marijuana, which she said could become similar to cigarettes.

"If you think about … big tobacco, it has taken us 50 years and billions and billions of dollars to get kids to stop smoking," said Ambrose.

"But now we would have big marijuana – it concerns me greatly."

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