Far-right presidential candidate Marine Le Len was confronted by a voter on Friday who demanded to know why she wanted to ban Muslim headscarves.
Incumbent candidate Emmanuel Macron was also asked about the proposed headscarf ban in a television debate.
The two are in a tightly contested presidential race with a vote on April 24, and some Muslims feel their faith has been unfairly stigmatised in the campaign.
At a farmers’ market in the southern town of Pertuis, a woman in a blue-and-white head covering approached Ms Le Pen as she wove past fishmongers and vendors to greet supporters.
“What is the headscarf doing in politics?” the woman asked.
Ms Le Pen defended her position, describing the headscarf as a “uniform imposed over time by people who have a radical vision of Islam” .
“That’s not true,” the woman said. “I started to wear the veil when I was an older woman … for me it is a sign of being a grandmother.”
The woman said that her father had served in the French military for 15 years.
Ms Le Pen’s opposition to the headscarf has encapsulated what her critics say makes her dangerous to French unity, by stigmatising millions of French Muslims.
She would also slash immigration and wants to outlaw ritual slaughter, which would restrict access by French Muslims and Jews to halal and kosher food.
Mr Macron exchanged views with a woman in a headscarf during an exchange on France-Info.
He sought to distance himself from Ms Le Pen’s policy by saying he would not change any laws, but he defended the existing ban on headscarves in schools as part of France’s secular principles.
The woman, Sara El Attar, said she had felt insulted by previous comments by Mr Macron in which he suggested that headscarves destabilise relations between men and women.
French women “have been castigated these recent years for a simple scarf, without any leader deigning to denounce this injustice”, she said.
She repeated the argument that many veiled women in France make – that people mistakenly think they are veiled, not through personal choice, but because men make them wear headscarves.
Mr Macron sought to defend his record. “For me personally, the question of the headscarf is not an obsession,” he said.
Critics say his government stoked prejudice against Muslims by cracking down on what it has claimed are efforts by some Muslims to carve out spaces in France for stricter interpretations of Islam.