TORONTO -- Social conservatives accuse Patrick Brown of "muzzling" the Progressive Conservative candidate in an upcoming Ontario byelection to downplay the party leader's flip-flopping on sex education.

Nineteen-year-old Sam Oosterhoff defeated the PC party president and a vice-president to win the nomination for the Nov. 17 byelection in Niagara-West Glanbrook, in part by campaigning against the province's updated sex-education curriculum.

Charles McVety, president of Canada Christian College, said Oosterhoff ran on a "socially conservative platform," and was talking about Ontario's sex-education curriculum when he vowed to stand up for parents as first educators.

"One of the issues that he had on his website was to stand up for parental rights in education," McVety said in an interview. "That's obviously directed at the whole sex-ed issue...but as soon as he becomes the candidate, all of a sudden Patrick doesn't allow him to speak on this, to speak his mind."

Oosterhoff has not responded to many requests for an interview since becoming the PC candidate, but Brown insisted he wasn't trying to keep the teenager from talking with political reporters about the sex-ed curriculum.

"I can tell you Sam supports the direction I'm taking the party," Brown said Tuesday. "We will make sure he's available at some point in the near future."

Queenie Yu, who ran as an independent in the Scarborough Rouge River byelection on Sept. 1 solely on the issue of repealing the sex-ed curriculum, is running again in Niagara-West Glanbrook, but isn't looking for votes.

Yu said she and other social conservatives believe Brown is not letting Oosterhoff speak to the media, so she's running "to help voters see whether Brown is telling the truth or not."

"I'm just being a voice for the issues that Sam believes in," said Yu. "I believe that Sam is against sex ed, but he's not allowed to talk about sex ed because of Patrick Brown."

After Oosterhoff won the nomination Oct. 22, Brown insisted the teen's victory was "absolutely not" revenge from social conservatives who are upset over his decision to support the Liberals' 2015 update to the sex-ed curriculum.

Rob Leone, a former PC member of the provincial legislature who is now an assistant professor of political science at the University of Western Ontario, said he doesn't think Brown is muzzling Oosterhoff. The PC leader is trying to keep the party focused on the big issue where the governing Liberals are vulnerable: rising electricity rates, said Leone.

"We have basically a teenager who out hustled two party veterans for a nomination and now we have a byelection and have to win it," he said. "And how you win it is not by dealing with internal strife, but by portraying one unified message to voters."

Progressive Conservative MPP Monte McNaughton, the most vocal opponent of the updated sex ed curriculum in the Tory caucus, said he'd never been muzzled by Brown for speaking out against the changes introduced by the Liberals.

"Parents' voices will be heard on this issue," he said. "My position certainly has never changed on this issue, but our leader has also made his views crystal clear, and he wants to focus on making life more affordable for families."

McVety called Brown "my personal friend" for a decade, when the PC leader had been a backbench MP in Stephen Harper's Conservative government.

Brown signed up thousands of social conservatives when he ran for the Ontario PC leadership by opposing the Liberals' sex-ed update, but then reversed position and "unilaterally declared that the party would be socially Liberal," added McVety.

"For 10 years he had a perfect record as a social conservative and he signed us all up and we worked hard, donated money, time and effort, and then after he got the power he said 'never mind,"' he complained.

"Bait and switch, and that's what he did with us."

Previous Conservative leaders who abandoned the social-conservative wing of the party paid the price in elections, including Tim Hudak and John Tory in Ontario and the late Jim Prentice in Alberta, warned McVety.

"If you abandon your voters, who's going to vote for you?" he asked. "Are liberals going to now say: 'Wow, he's socially liberal, are we going to vote for him?' No!"

The Conservatives fumbled the sex-education file during the Scarborough-Rouge River byelection after Brown's chief of staff distributed a letter saying a PC government would "scrap" the Liberals' updated curriculum.

Brown later disavowed the letter, saying that the local Tory campaign "went too far," but The Canadian Press obtained an email that his chief of staff, Nicolas Pappalardo, sent to Queenie Yu, with the letter attached.

The group Parents as First Educators, which said it had discussions with Brown's office during the Scarborough campaign about commitments he could make, complained Tuesday that it's now unclear where Oosterhoff stands on sex ed.

"By all accounts, Sam Oosterhoff is a fine young man of great personal conviction," PAFE president Tanya Granic Allen posted on the group's website. "We simply have no public evidence as to what those convictions are."