PARIS — Emmanuel Macron won the battle of the votes in Sunday’s parliamentary voting, but he hasn’t necessarily won the battle of the voices, and that could spell trouble for his pro-market agenda down the road.

Two of the loudest voices in French politics won election to Parliament in the weekend voting. Jean-Luc Mélenchon on the far left and Marine Le Pen on the far right were elected, and both have already promised to wage all-out war on France’s new president.

These populist orators and leaders of national movements in France will have only a fraction of votes in Parliament compared with Mr. Macron’s overwhelming 53 percent of representatives, known as deputies. But Ms. Le Pen and Mr. Mélenchon are potent voices with large constituencies in a country where Mr. Macron was only the second choice, at best, of a majority of citizens.

The two are experienced masters of rabble-rousing invective, skilled at inciting the fear and anger of millions. They are anti-Europe, anti-globalization, largely suspicious of capitalism, and in the case of Ms. Le Pen, fiercely anti-immigrant. Mr. Macron, on the other hand, is receptive to all four policy areas.