PARIS — A Muslim woman in a blue and white hijab confronted Marine Le Pen, the far-right presidential candidate, as she made her way through a crowd in the southern town of Pertuis last week. “What is the head scarf doing in politics?” the woman demanded.
Ms. Le Pen, a nationalist with an anti-immigrant agenda, has vowed to ban the wearing of the head scarf in public if she is elected in the second round of voting next Sunday. She says that it is “an Islamist uniform,” or a sign of adherence to an extremist, anti-Western interpretation of the Muslim faith.
The woman who argued with Ms. Le Pen was having none of this. Her choice to wear a head scarf was made, she said, “when I was an older woman,” as a sign of “being a grandmother.” Ms. Le Pen insisted that in many French neighborhoods women who do not wear a veil are “separated, isolated and judged.”
In the country with the largest Muslim population in western Europe, what a woman wears on her head matters. France has a troubled relationship with Islam because of its colonial history in Algeria and several jihadist terror attacks in recent years. As Ms. Le Pen and President Emmanuel Macron confront each other in a tight race, religious freedom, particularly for the Muslims who make up about 8 percent of the population, has emerged as a pivotal issue.
Mr. Macron, who has called Ms. Le Pen’s plan “an extremist project,” has nevertheless angered some members of the Muslim community, mainly through legislation designed to combat what he calls “Islamist separatism.” That law, passed last year, has been used to close some mosques and Islamic associations accused of fostering radicalism. It was designed in part to draw right-wing voters to his centrist camp.
Mr. Macron, whose lead in polls has widened slightly over the past week to 53.5 percent against Ms. Le Pen’s 46.5 percent, had his own confrontation with a young French woman wearing a hijab during a campaign stop in Strasbourg last week.
“Are you a feminist?” he asked. “Are you for the equality of women and men?”
When the woman answered yes to both questions, and said her head scarf was chosen, not imposed, Mr. Macron, clearly alluding to Ms. Le Pen, said this was the “the best answer to all the stupidity I keep hearing.”
It was another example of Mr. Macron, who scarcely campaigned before the first round of voting on April 10, adjusting his message to appeal to blocs of voters who have felt betrayed by him over the past five years — the Muslim community and the left.
In the first round, about 70 percent of French Muslims voted for Jean-Luc Mélenchon, the far-left candidate who was narrowly eliminated, according to a study by the Ifop polling institute. Where those votes now go matters.
France is a secular republic and in theory a nondiscriminatory society where people are free to believe, or not, in any god they wish. But it finds itself in a fracturing debate over Islam. A growing Muslim presence is seen by the extreme-right as a mortal threat to French identity, and this view has gained a foothold in the political mainstream.
Intensely attached to its model of a secular society, known as laïcité, which is supposed to subsume all men and women into the rights and responsibilities of French citizenship, France has been reluctant to acknowledge failures that have left many Muslim immigrants and their descendants in dismal housing projects on the periphery of big cities, feeling no viable French identity or future.
Since 2011 it has been illegal to wear a face-covering niqab, or a burqa covering the entire body, in public. But there is no ban on the head scarf.
French laws prohibit wearing ostentatious religious symbols — the head scarf is considered one — in schools. Civil servants are also barred from doing so on the job. Debate has raged over whether parents accompanying school trips should be allowed to wear head scarves, but attempts to stop them have failed.
Strongly held French feelings about the equality of men and women, about secularism, and about its supposedly colorblind society lie behind the virulence of the discussion of these issues. So does unacknowledged or overt prejudice.
Mr. Macron has accused Ms. Le Pen of undermining the principles of laïcité and the Constitution itself with the proposed head scarf ban. In an interview with Franceinfo radio last week, he said she would also have to ban the use of the “kippa, the cross and other religious symbols” in public or she would be discriminating among believers.
Not so, Ms. Le Pen retorted in an interview with France Inter radio. “The head scarf is in reality an Islamist uniform, it is not a Muslim uniform, and that makes all the difference. It is the uniform of an ideology, not of a religion.”
She continued: “This ban is not based on the concept of laïcité. It is based on the battle against Islamist ideologies.”
However, Ms. Le Pen appeared to hedge a little on Sunday, saying that the issue is a “complex problem” and that her proposed ban would be debated in the National Assembly.
Whether the ban would also apply to women choosing head scarves as fashion statements à la Audrey Hepburn is unclear.
Ms. Le Pen has said there would be no more difficulty in applying the ban, and fining women who wear head scarves, than there is enforcing the use of seatbelts.
If such comments drive Muslim voters away from Ms. Le Pen, it is far from clear that they will also drive them to support Mr. Macron in the second round. Many first-round voters for Mr. Mélenchon, Muslims among them, have said they will abstain on April 24.
In a radio debate last week with Mr. Macron, Sara El Attar, the founder of Hashtag Ambition and a communication coach, said comments by Mr. Macron suggesting head scarves damage relations between men and women had angered her as a Muslim woman who chooses to wear a head scarf.
French women “have been punished in recent years for a simple scarf, without any leader deigning to denounce this injustice,” she said.
Further envenoming the debate on religious freedom, Ms. Le Pen has promised to ban the ritual slaughter of animals required for the production of halal and kosher meat, a position rejected by Mr. Macron as heralding a France where “Muslims and Jews would be unable to eat as their religion instructs.”
In a joint statement last week, Haïm Korsia, the chief rabbi of France, and Élie Korchia, the president of the Israelite Central Consistory, said such a measure would, for Jews and Muslims alike, be “a serious attack on the free practice of religion that is a foundation of our Constitution.” They urged voters to back Mr. Macron.
Mohammed Moussaoui, the president of the Union of French Mosques, said ritual slaughter was “an aspect of the religious freedom” guaranteed by the Constitution. While condemning Ms. Le Pen, he did not say which way Muslims should vote.
The woman who confronted Ms. Le Pen in Pertuis noted that her father had served in the French military for 15 years. The enormous cemetery at Verdun, scene of one of the most devastating battles of World War I, has an entire section for French Muslims who died fighting for France.
As the debate over Islam’s place in France rages, this military service is seldom recalled, to the point that the position of Éric Zemmour — the now-eliminated hard-right candidate who held that Islam and France were simply “incompatible” — drew almost 2.5 million votes in the first round.
He has urged his followers to vote for Ms. Le Pen in the second round.
Aurelien Breeden contributed reporting.