Ontario's Progressive Conservative leader Patrick Brown says his changing position on the Liberal government's sex-ed curriculum may cost him the byelection in the Toronto riding of Scarborough Rouge River on Thursday.

A campaign letter distributed last week, just days before the byelection, said a Progressive Conservative government would "scrap the controversial changes to sex ed" if Brown wins the 2018 provincial election. On Monday, Brown admitted that letter was a "mistake."

Today, he told CBC's Metro Morning that the flip flop may damage his party politically.

"I realize this may cost me the byelection in Scarborough-Rouge River because much of the opposition was on this issue," Brown told host Matt Galloway on Tuesday.

"But I don't want to win a byelection on false pretenses. If I am premier, I am not going to be scrapping sex education."

Brown declined to say whether or not he actually wrote the letter that was sent out to constituents in the east Toronto riding.

"Ultimately on this issue, I wasn't hands-on enough," he said. "I'll take full responsibility for what my team put out there in Scarborough to some homes, but ultimately, it did not reflect what I would do if I was premier.

"I'll be honest," said Brown, "people told me, you know, you should wait to correct the record until Friday. I said no. I don't want anyone going to the polls on misinformation."

The candidates in the byelection include: Raymond Cho for the Progressive Conservatives; Piragal Thiru for the Liberal Party; Neethan Shan for the NDP; and Queenie Yu as an independent. This is a full list of candidates in the byelection.

The co-chair of Cho's campaign is Doug Ford, the former Toronto mayoral candidate and onetime councillor for Ward 2.

The curriculum was updated last year, for the first time since 1998, but some parents complained that the government didn't consult them enough and were angered by mentions of same-sex relationships, gender identity and masturbation.

Brown said he took to Twitter "as soon as possible" to correct the letter because he didn't want to be seen as trying to "curry votes." Brown said the updated curriculum is a "hot issue" in the riding.

"I realize some of my supporters in Scarborough are passionate about this issue," he said. "Ultimately, they went further than what I was comfortable with."

'Lack of communication'

Brown said he had a "heart to heart" with his caucus at a Kenora, Ont., retreat on the weekend about the letter that was sent out.

"There was a lack of communication," he said.

He said the Liberal government could have done a better job on consulting the public, experts and educators before updating its sex-ed curriculum. But he said he believes an updated curriculum is important.

Schools should be raising LGBT issues, educating students about combating homophobia, and talking about such issues as consent and mental health, he said.

"Those are all important things that need to be brought up in the school system today. The curriculum does need to be updated on a regular basis."

Brown said he was the first MP in Barrie, Ont.'s history to attend a Pride flag-raising and the first PC leader to march in Toronto's Pride parade.