TORONTO -- Voters head to the polls Thursday in a tight byelection race in east Toronto that has been dominated in the campaign's waning days by controversy over the government's sex-ed curriculum.

Parts of the new curriculum have been deeply unpopular in pockets of the province since it was introduced last year, in particular among some religious communities and new Canadians. Parents have protested and complained that the government didn't consult them enough, with some angered by mentions of same-sex relationships, gender identities and masturbation.

In Scarborough-Rouge River, where more than half of the population was born outside Canada and speaks Tamil or Chinese languages, the Progressive Conservatives are being accused of exploiting the curriculum's unpopularity for political gain.

A letter was distributed -- under leader Patrick Brown's name -- to residents saying that if the party forms government after the 2018 provincial election, they will "scrap" the Liberal government's changes to the curriculum.

Days later, Brown disavowed the letter, saying he didn't see it before it went out, and pledging that he would not scrap the curriculum. But the Liberals seized on it as evidence of Brown "flip flopping."

"Once again Patrick Brown demonstrated his unprincipled leadership by pandering to anti-sex ed activists a week before a byelection concludes, proving once again that he will say anything to anybody if he thinks that it is politically expedient," the Liberals charged.

Opposing the curriculum could hurt Brown provincially, but would play well in the riding, said Chris Cochrane, an associate professor of political science at the University of Toronto Scarborough campus.

It may not matter that Brown has distanced himself from the letter, he said.

The Liberals suggested that the letter had been translated into other languages and that people who received those copies would not necessarily see Brown's disavowal in the English media.

"That's the trick," Cochrane said. "Did the retraction catch on as much as the initial comment?"

This byelection will both serve to define Brown -- it's the first truly close race since he became leader -- and test Wynne's leadership at a time when, halfway through her term, polls show her as unpopular with voters, Cochrane said. But he also thinks the NDP stands a good chance.

In the 2014 election, Liberal Bas Balkissoon -- whose surprised resignation triggered the byelection -- won with about 39 per cent of the vote, but Neethan Shan wasn't far behind with 31 per cent for the NDP and Raymond Cho garnered 28 per cent for the Tories.

The latter two candidates are running again in the byelection, so will benefit from some name recognition in a race finally without an incumbent. Balkissoon held the riding since 2005 and before that Alvin Curling had represented the area for the Liberals since 1985.

Neither the Liberals nor the Tories made their candidate available to The Canadian Press this week for an interview. But the NDP candidate said the main issues for voters in the riding are: transit, jobs, soaring hydro bills and health care. He did not want to speak about sex ed.

"(There are) many more pressing issues such as expanding the Scarborough subway, hydro rates, auto insurance, school funding, health-care funding -- those are the major issues that I'm hearing on the ground."

Voters will choose from a whopping 11 candidates, including some vehemently anti-sex-ed fringe and independent candidates and a None of the Above candidate -- in both name and party.

The previous byelection in Whitby-Oshawa saw the leader of the None of the Above party duke it out for the disenchanted vote with a man who had changed his name to Above Znoneofthe so he could appear last in an alphabetical list of candidates on a ballot.

But the two have set aside their differences and Above Znoneofthe is running as a None of the Above party candidate in Scarborough-Rouge River.