The leader of Ontario's Progressive Conservatives, a largely unknown politician who polls suggest could be the province's next premier, says social conservative issues will be off limits at his party's much anticipated policy convention.

Patrick Brown, who as a former backbench MP in Stephen Harper's government voted in favour of reopening the abortion debate, has been busy trying to fend off Liberal attacks that he is a thinly disguised social conservative. But Brown says he is pro-choice and more recently has led Pride parade delegations.

"Any policy that attempts to limit a woman's right to choose or the ability of same-sex couples to marry are off limits, period," Brown said in an interview with The Canadian Press.

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"I'm not going to say it's even up for consideration when I personally could not defend that or support it."

The move says less about Brown himself and more about his sense of Ontario's political climate and what will get him elected, said Ryerson University political science professor Myer Siemiatycki.

"This is Mr. Brown responding to, I think, where the lay of the land is and public opinion is predominantly settling in Ontario that he can't win an election in Ontario by positioning himself as the candidate of social conservatism," Siemiatycki said.

Since becoming party leader in 2015, Brown says he has boosted party membership – it's now at 127,000 members, up from about 10,000 following the 2014 election loss – and believes the vast majority are on board with socially progressive policies.

"Frankly, I think I opened the party up to tens of thousands more who simply want a reasonable, thoughtful...modern, inclusive PC party," he said. "So I'm not worried about a few leaving."

In another effort to distance himself from social conservative policies, Brown published a video moments before the Liberal government announced legislation to create safe zones around abortion clinics, declaring himself pro-choice and saying he would support the bill. Party ads show clips of Brown repeating one of his often-used lines, that in the PC party "it doesn't matter who you love."

Social conservatives inside the party have accused Brown of flip-flopping on the issue of sex education – Brown spoke at an anti-sex-ed rally during the leadership campaign, promised in an e-mail to a supporter that he would repeal the updated curriculum, and later promised in a letter in a 2016 by-election to scrap it, though he later said he was unaware of the letter before it went out.

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There will be no sex-ed policy resolutions at the convention either, Brown said in the interview.

The Liberals are more than eager to remind voters of Brown's inconsistencies on social issues, accusing him last week of "double speak on abortion rights." It was just the latest in a long string of attacks that paint him with an extreme right wing brush, while polls show half the province doesn't know who he is – eight months before the provincial election.

The "shoe doesn't fit," Brown said.

"I was a backbench member of a broader team," he said of his time in the Harper government. "Now that I'm the leader of the party I can much (more) clearly speak from my own heart...Rather than criticize the fact that opinions have evolved, we should celebrate it."

Party members will vote online between Nov. 2 and 6 on 139 resolutions, with results announced at the Nov. 25 convention.

Carbon tax is another policy that will be off limits at the party policy convention.

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Brown has already promised he would dismantle the current cap-and-trade program to reduce greenhouse gas emissions and instead implement a carbon tax that would be offset by other tax cuts – to the chagrin of some of the base.

They bristle at the notion with complaints both privately and publicly through blog posts and websites such as Axe the Carbon Tax. A former PC caucus member who was either expelled or resigned cited the carbon tax as a main reason for joining the fringe Trillium Party. But Brown brushes off any suggestion it's a divisive issue.

"I think there's a broader understanding in the party that I staked out some ground that we are going to take climate change seriously, that we are going to support carbon pricing as part of the national framework, that we have to do our part on the environment, but it should not be used as a revenue grab by government," he said.