Justin Trudeau says a Liberal government would get to work "right away" on a policy to legalize and regulate the sale of marijuana, but won't commit to a timeline for legalization.

"We don't yet know exactly what rate we're going to be taxing it, how we're going to control it, or whether it will happen in the first months, within the first year, or whether it's going to take a year or two to kick in," Trudeau said on Wednesday night in Surrey, B.C.

When asked by CBC News for a specific time on the rollout of the policy, Kate Purchase, director of communications for Trudeau's campaign, said, "We haven't released a time.… We want to get the best ideas from various places and construct a Canadian model."

Purchase cited Colorado as one of many models the party is currently looking at.

In Colorado, an individual over the age of 21 is allowed to possess up to about 28 grams (one ounce) of marijuana for personal use.

When asked why the party has not accounted for tax revenues from marijuana in its financial projections, Purchase said, "We don't want to pre-suppose revenue."

Trudeau has previously suggested the Liberals don't have any plans to introduce marijuana-related policy during the campaign.

"We will continue to answer questions on this," said the Liberal leader. "But the policies we're putting forward are really focused on how we're going to grow the economy and give the kind of future to Canadians that they deserve."

NDP supports pot decriminalization

The NDP favours decriminalization rather than legalization of marijuana.

"I want to make sure that everybody understands that the NDP's position is decriminalization the minute we form government," Mulcair said in response to a question at a campaign event in late August.

Mulcair emphasized his party's long-standing commitment to decriminalization.

"The NDP has had the same position for about 40 years," Mulcair said in August. "Decriminalizing marijuana is the position of the NDP, it's my position and it's something that we can do immediately."

A majority of Canadians are in favour of either decriminalizing or legalizing personal marijuana use, according to the latest findings of Vote Compass, CBC's voter-engagement survey.

Conservative Leader Stephen Harper says that in jurisdictions where marijuana is legal, the drug becomes "more readily available to children, more people become addicted.

"We just think that's the wrong direction for society, and I don't think that's the way most Canadians want to deal with this particular problem," Harper said.