French leader Emmanuel Macron and challenger Marine Le Pen qualified on Sunday for what promises to be a very tightly fought presidential election runoff on April 24, pitting a pro-European economic liberal against a far-right nationalist.

With partial results putting Macron in first place ahead of Le Pen after the first-round voting, other major candidates admitted defeat. Except for another far-right candidate, Eric Zemmour, they all urged voters to block the far-right in the second round.

But after five years in power in which his abrasive style has...