Photographs of lobster tails on a table set with sparkling crystal at the Hôtel de Lassay, the assembly president’s official residence, and of Mr. de Rugy’s wife, Séverine, smiling next to a bottle of wine worth about $560, had a devastating effect. The Yellow Vests, who rose up in revolt precisely over outrage at the perceived overprivilege of the Paris political and economic elite, were back on Sunday, demonstrating on the Champs-Élysées during the Bastille Day celebrations and yelling, “We want lobsters, Champagne and caviar.”

Mr. de Rugy lashed out at Mediapart over the revelations. Mr. Macron himself is known to dislike the website, to have disdain for journalists in general, and to hate appearing to cave in to articles that challenge him.

As late as Monday, Mr. Macron appeared to be standing by his minister, proclaiming, “I don’t make decisions based on revelations, but on facts, otherwise we turn into the Republic of Denunciation.”

In a similar vein, a year ago Mr. Macron resisted for weeks responding to what proved to be one of the most damaging scandals of his presidency: One of his personal security guards, Alexandre Benalla, was caught on camera hitting a protester during a demonstration. Mr. Macron initially brushed away the revelations, but the president’s fumbling response gave his critics ammunition.

Over the weekend, discontent within the president’s political movement over the de Rugy scandal grew steadily, with some lawmakers expressing fears about the damage it was causing to them and Mr. Macron.