For years, the far-right National Rally tried to distance itself from Mr. Le Pen’s racist and antisemitic remarks. But after his death Tuesday, it hailed him as a visionary.

He co-founded what became France’s biggest opposition party, National Rally, rooted in deep anti-immigrant sentiment.

The death of Jean-Marie Le Pen, former leader of the party once known as the National Front, occurs at a time when the mainstreaming of far-right politics in France seems almost complete. Le Pen was,