"Should you have to hide your face to vote NDP?" the ad asks in French.
The text is superimposed on an image of the House of Commons through the eyeholes of a black niqab, the full-face covering worn by certain Muslim women.
Earlier this month, the Federal Court ruled that women can wear a niqab when taking their oath of citizenship, after a woman brought a case objecting to the 2011 law requiring her to remove it during the ceremony.
The woman argued it requires her to temporarily abandon her Sunni Muslim belief, and that female officials could easily take her oath in private, because the law doesn't require people to be "seen" taking it.
In front of a receptive audience in Victoriaville, Que., on Feb. 12, Prime Minister Stephen Harper announced the federal government would appeal the ruling.
Liberal Leader Justin Trudeau and his Liberal Party were quick to condemn the decision to appeal, saying the Conservatives were pandering to fears about Muslim Canadians in an effort to sway votes.
Then Wednesday, NDP Leader Tom Mulcair took a stand as well. Answering a reporter's question in French, he pointed out the context for Harper announcing his appeal, and said there was "vilification" in the government's policy.
"I see that Muslims are often scapegoats for political debate. And that, I find it heartbreaking," he said in French.
The issue is particularly heated in Mulcair's home province of Quebec, where first a "reasonable accommodation" bill and then the PartiQuébécois's failed secular charter provoked divisive partisan debate, rallying those uncomfortable with visible and public aspects of multiculturalism.
Last month, the PQ announced it will revive a religious neutrality bill, calling Liberal Premier Philippe Couillard's inaction on the issue unacceptable.
The latest advertisement from their federal counterparts suggests Harper's Conservatives aren't the only ones targeting voters holding these views for electoral gain.
In the 2011 election, Quebec voters drifted away from the BQ in favour of the surging New Democrats, then under "Le bon Jack" Layton's leadership.
The separatist party never recovered from the "Orange Crush" that reduced the BQ to a handful of seats and cost it official party status in the Commons. Under new leader Mario Beaulieu, it is still languishing in public opinion polls compared with its previously dominant status among Quebec's federal seats.
Beaulieu reacted strongly to Mulcair's comments Wednesday, calling his views the "fundamentalist multiculturalism" of an apostle and "disturbing cultural relativism."
"We believe that the face should be uncovered when you become a citizen, as when voting. This, it seems to me, is the least of things," he said in a French statement reported by La Presse Canadienne.
The decision to appeal was featured in Conservative fundraising emails and on social media.
Messages under Immigration Minister Chris Alexander's name made reference to not only the niqab, which covers the face, but also the more common hijab, which covers women's hair but leaves the face visible.
Before entering politics, Alexander was Canada's ambassador to Afghanistan.