BRUSSELS (AP) -- An influential French member of the European Union's powerful executive branch resigned on Monday, criticizing the leadership of European Commission President Ursula von der Leyen just as she tries to assemble a new team for the next five years.

Thierry Breton, a French business executive and commissioner for the EU's vast internal market who recently clashed with tech billionaire Elon Musk, suggested that von der Leyen had gone behind his back to get another French official named in his place to the next commission.

In a post on X that contained his resignation letter to the EU's top official, Breton said that von der Leyen's move was "further testimony to questionable governance -- I have to conclude that I can no longer exercise my duties in the College."

The commission proposes legislation for the EU's 27 member countries and ensures that the rules governing the world's biggest trading bloc are respected. It's made up of a College of Commissioners with a range of portfolios similar to those of government ministers, including agriculture, economic, competition, security and migration policy.

Breton's surprise resignation came just 24 hours before von der Leyen was due to announce her new team to the European Parliament. The commission was scheduled to start work on Nov. 1, but speculation is rife that it might not get down to business before January.

European Commission spokeswoman Arianna Podesta said that von der Leyen had accepted Breton's resignation and thanked him for his work during her first term. Podesta declined to comment on his very public criticism of the president's leadership.

Within hours, President Emmanuel Macron nominated France's foreign minister, Stéphane Séjourné, in Breton's place. The commission couldn't say who might take over Breton's responsibilities, which have included efforts to expand Europe's defense industry to make more weapons and ammunition for Ukraine.

With an eye to keeping a gender balance within the commission for her second term at the helm, von der Leyen had asked each member country to supply the name of a male and female candidate for policy commissioner. Most only proposed one candidate, often a man.

Von der Leyen, a former German defense minister, has been pressing smaller countries to change their minds. In recent weeks, a man who was the preferred candidate of the government in Slovenia withdrew and a woman was proposed in his place.

But France is no small EU country. It ranks, along with Germany, at the top of the bloc's political heavyweights.

Von der Leyen decides which country gets which portfolio, and some of them, like those involving trade or finance or EU enlargement, are coveted by certain countries. Plum jobs like the post of vice president -- the commission has seven of these -- are also much sought after.

Breton suggested that he was a victim of these political machinations.

"A few days ago, in the very final stretch of negotiations on the composition of the future College, you asked France to withdraw my name -- for personal reasons that in no instance you have discussed directly with me -- and offered, as a political trade-off, an allegedly more influential portfolio for France in the future College," he wrote in his resignation letter.

"You will now be proposed a different candidate," he said, without elaborating.

In any case, nothing is set in stone. The commission nominees must still pass a grilling in the European Parliament to take office.

Macron helped von der Leyen to claim one of Europe's most coveted jobs and has consistently supported her throughout her first term in office. It's unclear why she might risk defying the French president, if indeed she has.

Breton has irritated some in the commission with his go-it-alone approach. Acting last month without von der Leyen's approval, he took to X to warn Musk of possible "amplification of harmful content" by broadcasting an interview with former U.S. President Donald Trump.

Musk, who owns the social media platform, posted a derogatory reply. Trump campaign spokesperson Steven Cheung urged the EU to "mind their own business instead of trying to meddle in the U.S. presidential election."