Progressive Conservative Leader Patrick Brown issued a statement late Monday admitting he was "mistaken" in opposing Ontario's new sex-ed curriculum, after it emerged that he promised a social conservative supporter to repeal it — a position he had previously denied ever taking.

"Yes, my views on Ontario's sexual education curriculum — and similar issues — have evolved," Brown said in a statement.

"I opposed the changes to the curriculum ... Time and the evidence of my own eyes tells me that I was mistaken," he wrote, adding that he now strongly supports the curriculum but still "deplore[s] the absence of consultation with parents."

That's a stark contrast to what Brown wrote during the party's 2015 leadership race in an email to Jack Fonseca of Campaign Life Coalition.

"I will repeal it!" Brown wrote then. "I say that everywhere."

At the time, Brown wrote that then-leadership opponent Christine Elliott "thinks I am wrong for party given mine and (MPP Monte McNaughton's) opposition to sex education."

I think he's an amateur. I think he doesn't know what the heck he's doing. - Jack Fonseca , Campaign Life Coalition

​Fonseca said he also heard Brown make the promise to repeal out loud to others.

"Indeed he did say that everywhere when he spoke to groups and individuals and social conservative leaders," Fonseca said. "He told them all he would repeal it."

On Monday night, Brown responded directly to Fonseca's claim.

"I'm sorry that Mr. Fonseca and members of his group are upset. But I'm running to lead all Ontarians," he said.

"If the price to be paid is that my political opponents will say I've 'flip-flopped,' so be it. If you want a rigid ideologue as premier, vote for someone else."

Criticism about lack of consultation, not curriculum: Brown

Monday's statement appears to lend further weight to the argument Brown made recently, that a letter distributed during a the Scarborough-Rough River byelection under his name promising to "scrap" the curriculum did not reflect his views.

When asked last week when his views on sex-ed changed, Brown said he has always taken a "middle of the road" approach, criticizing the government for not consulting parents enough, but not on the need for the curriculum.

Brown has said he was livid to see his name attached to that position and disavowed it, but emails from his chief of staff appear to suggest the Progressive Conservative leader was aware of the promise.

During the fall-out from the controversial letter, Brown wrote in an op-ed that the local byelection campaign office had gone "too far" in writing that he would scrap the curriculum. But emails obtained by The Canadian Press show Brown's chief of staff, Nicolas Pappalardo, distributed the letter the day before it became public.

And in an email from the week before, Brown said he became aware of the letter Pappalardo wrote that Brown himself "was prepared" to make a statement saying, "If elected, a PC Government would introduce a new curriculum after thoughtful and full consultation with parents."

Brown has betrayed social conservatives, critic says

By backtracking on his promise to scrap the Liberals' sex-ed curriculum, Brown has betrayed social conservatives, Fonseca said.

"He's a politician.who doesn't stand for much at all — it's whatever the political winds lead him to believe will bring him more power or help him maintain power," he said.

"I think he's an amateur. I think he doesn't know what the heck he's doing."

Fonseca said he has "no doubt" Brown knew about the controversial letter before it went out.

Meanwhile, Brown says his about-face on the curriculum is evidence of his strength as a "pragmatic Progressive Conservative."

"There are plenty of political experts who will say this is weakness. I think Ontarians are more reasonable."

The new curriculum included updates such as warnings about online bullying and sexting, but protesters have taken issue with discussions of same-sex marriage, masturbation and gender identity.

A coalition of groups that oppose the curriculum is planning a rally at the legislature Wednesday, with MP Brad Trost, who has said he will run for leadership of the federal Conservative party, as one of several "special guest speakers."