A few weeks ago, French President Emmanuel Macron was a shoo-in for reelection. No longer. The far-right candidate Marine Le Pen is snapping at his heels; if she comes second in Sunday’s vote, she will go head-to-head with Mr. Macron in a closely fought second round in two weeks’ time.

She owes her success to a well-run campaign that has focused on the cost of living more than on her habitual bugbears, Islam and immigrants. That has smoothed the corners of her extremist image.

Mr. Macron, meanwhile, has seemed distracted by his diplomatic efforts to stop the war in Ukraine, and he has found it hard to shake off the impression that he is an aloof “president for the rich.”

Behind the extraordinary prospect that Ms. Le Pen might become the next president of France is an equally extraordinary dispersal of French voters. Eight of the 12 presidential candidates are right-wing nationalists or left-wing anti-capitalists, well to the right or well to the left of the traditional mainstream. Between them they command more than half the national vote.

Mr. Macron came to power in 2017 as a novel, radical centrist, elbowing aside the moderate socialists and conservatives who had ruled France throughout the 20th century. In office he has barely dealt with their political parties, effectively reducing them to irrelevance.

In exploding the political landscape, Mr. Macron blew up the political center. He can scarcely complain now if he finds himself alone as the only real bulwark against extremism. The question is, will that bulwark hold?

For more on the French elections, you will find an article in today’s Daily by Paris reporter Colette Davidson, exploring why French politics have been moving rightward despite the priority that voters put on left-wing values.