The resonance of Mr. Valette’s petition hardly came as a surprise to pollsters who have surveyed the public on this question on several occasions in the past couple of years. One 2016 poll by IFOP, a major French pollster, found that 69 percent of those surveyed did not want an official role for the first lady, said Jérôme Fourquet, the director of opinion polling for the organization. People were particularly allergic to the idea that she might be paid — although that was not one of Mr. Macron’s proposals. Another poll found similar percentages.

Beyond the stated arguments are both history and a French culture that even as it embraces a monarchlike president, remains leery of going too far down that road. It reminds people of some of the most violent and bloody periods in French history, including that of Louis XVI and Marie Antoinette, who were beheaded during the French Revolution.

“There’s a complicated rapport between this country and the monarchy,” Mr. Fourquet said. “For the French,” he said, “to give power to a spouse goes back to monarchal power: The French elect a man, not a family. The notion of a couple reminds them too much of the monarchy and the royal couple.”

Adding to the complexity is an ambivalence over how much the French want to see or know about the first lady.

“The French respect that it was the husband who was elected by the people,” Mr. Fourquet said. “So the woman is present ‘in the photo,’” he said.

From an American perspective, the French furor over defining an official position and responsibilities for the first lady looks like a tempest in a teapot: First ladies, whether Republican or Democrat, at least since the presidency of Herbert Hoover, have pushed boundaries — some more than others. And while controversy dogged some of them, they have gradually become more and more accepted as public figures.

While there is no statute in the United States defining the first lady’s role and the position is unpaid, since 1978, when President Jimmy Carter signed a law authorizing a budget and a staff, it has become accepted that the presidential spouse has a number of duties and needs assistance to carry them out. Recent first ladies have had staffs of 16 to 25 people, according to a report on the office of the first lady for Rice University’s Baker Institute in 2016.