Canada's national election is in two weeks, and there's a somewhat unusual issue currently dominating much of the campaigning: Muslim women who cover their faces for religious reasons.

Prime Minister Stephen Harper, a member of the Conservative party, has for months been decrying the wearing of the niqab, particularly by immigrants during citizenship ceremonies. The face-covering garment is "rooted in a culture that is anti-women," Harper said earlier this year. Wearing it when "committing to joining the Canadian family," according to the prime minister, "is not the way we do things."

Now, it's not as if there's an epidemic of Muslim women wearing niqabs to Canadian citizenship ceremonies. But in the past months, and especially the past few weeks, the niqab issue has become a huge part of Harper's campaign. What's more, it appears to be working — raising some pretty disturbing questions about how Canada sees Muslims and immigrants.

How the niqab issue came up, and where it came from

Unlike a standard headscarf, a niqab covers both a wearer's hair and face, excluding the eyes (this BBC illustrated guide is helpful if you're confused). It's not especially common among Muslims in North America — but one woman, named Zunera Ishaq, wanted to wear it to her Canadian citizenship ceremony in January 2014.

She wasn't allowed. Back in 2011, Harper's government had banned the wearing of niqabs during such ceremonies, and Ishaq couldn't become a citizen until she underwent the ceremony. That forced her to choose between wearing clothes she saw as a religious obligation and becoming a citizen in her adoptive country. Ishaq sued the government, arguing that this policy violated her rights — and this February, she won. That was the beginning of the 2015 niqab controversy in Canada.

The issue really took off in mid-September, when the Federal Court of Appeal upheld the lower court's ruling that the ban was illegal. Election season was in full swing at that point. And while the courts had sided against Harper, voters had not. A March poll found that 82 percent of Canadians supported a ban on the niqab during citizenship ceremonies.

Harper vowed to take the case to the Supreme Court. Conservative Party candidates, meanwhile, have emphasized that they will protect "Canadian values." The party website has a petition drive focused on the niqab issue (the URL: "not-the-way-we-do-things-here/").

A few days ago, Harper's government proposed a specialized tip line for reporting "barbaric cultural practices," which it said included honor killings. It has also proposed stripping citizenship from Canadians convicted of terrorism.

This is really about fear of immigration and Muslims

Harper and his party have framed the niqab issue as being about women's rights, but from that larger context it's pretty clear that this is actually about fears of immigration — specifically Muslim immigration.

According to Statistics Canada, 21 percent of Canadians are foreign-born, a significantly greater number than in other Western states such as Germany (13 percent) or the United States (about 12.9 percent).

The majority of recent immigrants are from Asia, defined as including both the Middle East and the Indian subcontinent. There's also been a recent influx of immigrants from Muslim-majority African countries, including Algeria, Morocco, and Nigeria.

For Canadians who oppose immigration or fear any changes it will bring, anti-Muslim sentiment has become a way of expressing those attitudes. A 2013 poll reported by Maclean's found that "attitudes toward Islam have deteriorated markedly across the country over the past four years," while attitudes toward other religions hadn't changed much at all. A majority of Canadians in that poll, 54 percent, had an "unfavorable view" of Islam.

Harper's campaign against the niqab, then, is either an expression of that sentiment, a deliberate effort to exploit it for political gain, or perhaps both. By focusing on the niqab, and objecting to it on grounds that sound feminist (though their argument in facts treats Muslim women as lacking the free will to choose their own clothing), the Conservatives are dressing up his anti-immigrant rhetoric in language that's palatable to famously left-wing Canadians.

The Canadian press, particularly on the left, is quite angry about this. Harper is "relentlessly fanning hostility toward Muslims, targeting them and pandering to nativist sentiments," the Toronto Star, Canada's largest daily paper, stated in a particularly angry editorial. "These spiteful Conservative policies — hound Muslim women, strip Muslim wrongdoers of basic human rights, shove Muslim refugees to the back of the line — have hijacked and distorted this election."

But so far, it's not stopping Harper from harping on the niqab. And there's a simple reason why.

The politics of this seem to be working for Harper

Back in early September, Harper's two rival parties — the center-left Liberals and left-wing New Democratic Party (NDP) — were beating Harper. Their respective leaders, Justin Trudeau and Tom Mulcair, oppose the niqab ban and generally take more open views on immigration.

Since mid-September, the Canadian Broadcasting Corporation's poll average shows Harper surging, particularly at Mulcair's expense.

There are any number of reasons for the poll shift in this election, just as in any election, but one lesson many seem to be drawing here is that Harper's rhetoric on the niqab has been effective.

"The Conservatives' emphasis on the defence of what they call 'Canadian values' is credited by pollsters with a significant uptick in their support, particularly in Quebec," the CBC's Terry Milewski reports.

In other words, these fears about immigration are real — and politically potent.