If hell hath no fury like a woman scorned, best look out when that woman happens to be both French and Marine Le Pen. The firebrand leader of the National Rally party in the Assemblée Nationale threw a right hook at President Macron — who beat her in France’s two most recent presidential elections — by questioning his capacity to defend the country.

Ms. Le Pen did this while her party is leading in polls above the first round of a hotly anticipated parliamentary vote on Sunday.  On Thursday Madame Le Pen called into question Mr. Macron’s ability to manage the country’s armed forces when she told the newspaper Le Télégramme that the French constitution states that the “the prime minister is responsible for national defense.”

While seemingly innocuous, they are fighting words because they call into question the French president’s authority to manage the country’s nuclear arsenal and its troops and military personnel in France and in hot spots around the world. She made the remark while her party, the far right National Rally, is leading in the polls. 

According to the most recent TFI television poll, 36 percent of voters surveyed intend to vote for the National Rally on Sunday. The left-wing alliance, the Nouveau Front populaire, is trailing at just over 28 percent, while the center-left parties allied with President Macron are far behind at just 21 percent. 

Those numbers indicate that Madame Le Pen’s party is poised to deliver a knockout punch to Mr. Macron. It helps explain her audacity in raising constitutional matters ahead of the vote. She knows that if the National Rally secures an absolute majority in the Assemblée that Mr. Macron will have little choice but to appoint the official party leader, Jordan Bardella, as France’s next prime minister. 

So is Madame Le Pen playing with fire by evoking  military matters now? Not really. She also stated that “the president of the Republic is the head of the armed forces” and is the one who “chairs the councils and higher committees of national defense.” Her comments about the prime minister’s role, though, also appear to be correct. There is a certain amount of ambiguity the constitutional division of labor.

Madame Le Pen is leveraging that to the hilt. She is a canny political operator. It stands to reason that she has a bigger bœuf with Mr. Macron than does Giorgia Meloni, although Italy’s prime minister tends to be more vocal about the various things about the Frenchman that rankle her. 

Immigration and the economy are at the front and center of the snap legislative election that was, after all, called by Mr. Macron. Foreign policy figures less prominently, although Mr. Bardella says his party will continue to support Ukraine. He also said in a debate on Thursday that “If I am prime minister tomorrow, French soldiers will not be sent to Ukraine.”

That message contradicts Mr. Macron’s refusal to rule out that possibility, but Mr. Bardella and Madame Le Pen know how to read a room — and a country. For a majority of French, the conflict in Ukraine, though significant, is distant, and they have more quotidian concerns like soaring food prices and crime. 

The more Marine Le Pen can show that Monsieur Macron is out of touch with everyday French reality, the better the prospects for a big victory on Sunday. The upper echelons of the French defense establishment will be among those watching closely.