Former White House strategist Steve Bannon, a champion of Donald Trump's "America First" agenda, will address the National Front's party congress on Saturday, a senior official of the French anti-immigrant party said.
"Let them call you racists, let them call you xenophobes, let them call you nativists, wear it as a badge of honor", Bannon told members of the anti-mass immigration party in video published by The Washington Post.
He also praised Le Pen's vision of a political spectrum that is no longer left- right but nationalists versus globalists.
She has long sought to "de-demonize" the party by moving away from its racist past, but Le Pen's own father complained that Bannon was the "most radical" of Trump's advisers, saying Saturday's invitation "is not exactly the definition of 'de-demonization'".
"The tide of history is with us, and it will compel us to victory after victory after victory", Bannon claimed.
Le Pen is seeking to make over her struggling party after her failed presidential bid a year ago.
In this photo taken on January 27, 2016 in Saint-Cloud, west of Paris France's far-right Front National (FN) party founder Jean-Marie Le Pen poses for a photograph.
National Front leader Marine Le Pen is working to unite her divided party and bolster her ability to lead it as the party meets for the first time since she lost resoundingly to Emmanuel Macron in the final round of the French presidential election last May.
The name is expected to be unveiled only on Sunday, shortly before the party delegates vote on it.
The changes pave the way for a younger leadership circle to emerge, even if the party's ideological foundation remains unchanged: nationalist, identity-driven, anti-European Union, according to Jean-Yves Camus, an expert on the far-right.
Bannon spoke at the National Front's annual convention in the French city of Lille after traveling through Europe in recent weeks for meetings with populist leaders of various parties.
But Bannon might have threatened Le Pen's makeover with his compliments for an extreme version of the National Front and lavish praise for Le Pen's more hard-line niece and rival.
On some level, the speech presented another development in the transatlantic relationship between far-right movements in the United States and Europe, particularly in France.
"Today's politics can not be summed up by the left-right divide".
The weekend congress is expected to erase one persistent problem for Le Pen - her unpredictable, bombastic father - by eliminating his title of honorary president-for-life from party statutes.
The party's deputy president Louis Aliot was the one who shed light to the explosive news about Bannon's speech on the first day of the conference.
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