NDP Leader Tom Mulcair said he supports the current requirement that women show their faces at some point in the citizenship process but that they should not be forced to remove a face covering while taking the oath of citizenship.
"I am in agreement with the existing rule under which anyone seeking citizenship must uncover their face to identify themselves before swearing the oath, in accordance with their religious beliefs," he said during a speech Wednesday in Montreal, adding that he understands some people may see the niqab as a symbol of oppression.
"If some of those women are oppressed, we need to help them, and it's not going to be depriving them of their Canadian citizenship and rights that will do that."
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Mulcair made the speech to clarify the NDP's position on the issue, one day ahead of the first French-language leaders' debate before the Oct. 19 vote.
The Conservatives have tried to impose a ban on niqabs and other face coverings during the oath of citizenship. Last week, an appeals court upheld a lower court's previous decision to strike down the ban.
The federal government has since said it will seek a stay of the court's decision until it can take the case to the Supreme Court of Canada.
Liberal Leader Justin Trudeau has said on the campaign trail that a Grit government would not appeal the striking down of the ban.
Until today, however, there was some controversy over Mulcair's stance.
"And on that, let me be clear: no one has the right to tell a woman what she must — or must not — wear," Mulcair said.
The NDP later confirmed to CBC News it would not pursue the issue of niqabs at citizenship ceremonies at the Supreme Court.
The issue is particularly contentious in Quebec, where a majority of people seem to be in favour of the government's proposed ban. Ninety per cent of Quebecers who responded to a question on the issue in Vote Compass, CBC's online voter engagement survey, said they were opposed to facial coverings in citizenship ceremonies.
Conservative Leader Stephen Harper has repeatedly said on the campaign trail that the "overwhelming majority" of Canadians support a ban.
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For his part, Mulcair has had to negotiate a tricky path thus far on the issue. His party needs to retain the hard-won votes it secured in Quebec in 2011 but cannot risk losing support in the diverse suburbs of Toronto and Vancouver, where voters appear to be opposed to the government's effort to impose a ban.
Mulcair accused the Conservatives of using the proposed ban to drive a "wedge" between voters, saying it's "an emotional issue that only affects a very small number of citizens in a very specific situation."
"Attacks, insinuations, campaigns of fear, complete scorn for our institutions. They are the stock and trade of this government," he said.
"It seems to me that Canada and Quebec deserve better than wedge politics, the politics of division."
How to watch Thursday's debate
The French-language leaders' debate will be broadcast live and live streamed online 8 p.m. to 10 p.m. ET Thursday.
You can watch the debate in simultaneous English translation on CBC News Network and online at CBCNews.ca/Canada Votes. The debate will be broadcast in French by Radio-Canada (check local listings) and live streamed online at ICI Radio-Canada.ca.