As candidates for the Conservative Party's leadership race continue to line up, an issue has emerged that many thought the Tories had put to bed a long time ago — the legalization of marijuana.

Former prime minister Stephen Harper called marijuana "infinitely worse" than tobacco. "If we sell marijuana in stores like alcohol and tobacco, that will protect our kids? No one believes that," he said.​

But last week Maxime Bernier injected a slightly unexpected element into the race when he suggested he was leaning toward supporting a Liberal motion to legalize possession of marijuana for recreational use, as has already happened in four U.S. states and the District of Columbia.

"I think it must be time to have a discussion with that," he told Rosemary Barton, host of CBC News Network's Power & Politics. "I am happy that this government will bring a bill."

"I am more for it" than against it, he said. "It depends how the government will do it. At the end I will decide whether I will vote for it or against it. But I am more toward — for — that."

That position sets Bernier at odds with his party's long-held opposition to loosening the laws against recreational use of marijuana.

Law unpopular with Tory voters

According to Vote Compass, CBC's voter-engagement survey, about 37 per cent of Conservative voters in the last election said they supported the full legalization of marijuana.

Another 38 per cent of Conservatives supported the NDP's position of decriminalization of marijuana — a step short of legalization that would treat pot possession similar to a traffic offence.

Only a quarter of Conservative voters agreed with Harper's position that marijuana possession should remain a criminal offence — a number that drops to 14 per cent across all voters.

These numbers suggest there is an audience within the Conservative Party for a more libertarian viewpoint — like the one Bernier is pitching.

On the other side of the debate is Bernier's only other declared rival, former minister of labour Dr. Kellie Leitch. She is one of the few Conservatives who have continued to thunder against the impending legalization of marijuana since the party's electoral defeat in October 2015.

"Health Canada spends hundreds of millions of dollars every year to encourage Canadians to stop smoking. Now the government wants Canadian kids to have access to a drug to smoke, marijuana," she told the House of Commons in February. "Parents are scared and concerned for their children. The government is sending out mixed signals."

Indeed, the Liberals have been criticized by advocates of marijuana reform for maintaining the current criminal penalties while they take their time drafting a legalization plan, rather than moving immediately to decriminalize as an interim measure.

Not clear where leader stands

Also sending out mixed signals is interim Conservative Leader Rona Ambrose.

As Harper's health minister, Ambrose often found herself fronting the party's anti-legalization approach, including the "reefer madness" strategy of linking marijuana use to mental illness.

So an interview she gave in January to Vancouver radio station CKNW caused considerable confusion about her position.

"The bottom line is there's a huge faction of people in this country that want — that are mostly adults, to be frank — that want access to pot and they want it legalized and it's for recreational purposes."

Ambrose then said she hoped the Liberals would push ahead faster to regulate storefront pot dispensaries that have sprung up around Vancouver.

"I hope the faster they move on this the better, because the proliferation of pot dispensaries is quite large, so it has moved now not just in Vancouver but across the country, and they're unregulated. So the sooner they can move on that, the better to protect kids."

Conservatives later explained that Ambrose was merely recognizing the inevitability of legalization, and encouraging the Liberals to get on with it. But government supporters jumped on what they saw as another Conservative post-election reversal.

"Health minister who spent millions of your $ on misleading ads against pot wants us to legalize faster," tweeted Trudeau's principal secretary Gerald Butts.

Will the vote be whipped?

It remains to be seen whether marijuana will become an issue in the Tory leadership race, or if members who dissent from the official party line will be able to express those views in Parliament.

Asked whether the party intends to allow a free vote when marijuana reform finally comes before the House, Ambrose's director of communications Mike Storeshaw told CBC News no decision has been taken.

"Decisions on caucus positions for legislation aren't made until there's actually legislation to consider, and we don't appear to be anywhere near that point yet."