But their lingering presence in Ms. Le Pen’s inner circle has called into question the sincerity of her strategy to “un-demonize” her party and renounce its heritage of deep-rooted anti-Semitism since she took over from her father, Jean-Marie, in 2011.

“By the evidence,” said the historian Nicolas Lebourg, a leading National Front specialist at the University of Montpellier, “she considers it’s not something very important.”

The two trusted men continue to work closely with the party’s top leadership, including Ms. Le Pen. They have been charged by French prosecutors in an elaborate campaign-finance scheme that has been crucial to keeping the National Front afloat for years.

The financial scandals have not dented Ms. Le Pen in the polls before the first round of voting on April 23. Potentially more damaging may be the recent revelations about the people she has surrounded herself with, in particular Mr. Chatillon and Mr. Loustau.

“They have remained National Socialist,” said Aymeric Chauprade, once Ms. Le Pen’s principal adviser on foreign affairs until a falling out, partly over his pro-Israel stance.

“They are anti-Semites, nostalgic for the Third Reich, violently anticapitalist, with a hatred for democracy,” he added in an interview. “People think they’re marginal. But in fact, I discovered, she protects them. She supports them. They are at the heart of everything.”

Mr. Chauprade recalled a dinner with Mr. Chatillon and others in the spring of 2014 that was “full of anti-Semitic jokes.” But he added: “They are not joking. They are real Nazis.”