PARIS — Insults and rumors keep coming: His speeches are too long and full of feel-good banalities. He does not have a real program. His time in government was a failure. He is secretly gay. He is developing a personality cult. He favors capitalism, and besides, he is too young.

If any surer sign was needed that Emmanuel Macron, the 39-year-old former minister of the economy, is the new front-runner in France’s presidential race, look no further than the concentrated volley of wild attacks against him. Even the Russians, via pro-Kremlin websites, are piling on.

France’s two major parties, on the right and the left, are in self-inflicted ruin, the first downed by the corruption scandal surrounding François Fillon, and the second by a utopian dreamer, Benoît Hamon.

Mr. Macron has glided artfully unto the breach. The youthful Mr. Macron is increasingly seen as the one who will turn back the tide of authoritarian populism, the nonpolitician who will defeat Marine Le Pen of the far-right National Front.