It is a time of extreme right-wing endorsements for the front-running Republican candidate Donald Trump. First, former Grand Wizard of the Ku Klux Klan David Duke announced his support, now France's uber conservative Jean-Marie Le Pen is backing Trump.

"If I were American I would vote for Donald Trump. May God protect him," tweeted the 87-year-old founder of the National Front party, now led by his daughter, Marine.

Le Pen was ejected from the party after a bitter feud with Marine over his inflammatory and racist comments. His daughter is trying to overhaul the FN's image as a more moderate party to appeal to more voters.

But Le Pen himself remains an unrepentant right-wing provocateur. Last year he repeated previous comments about Nazi gas chambers being a "detail" of history. He said in 2014 that Ebola could clear up Europe's immigration problem "in months."

Trump just caused a stir when he ducked denouncing an endorsement from former KKK Grand Wizard David Duke and professed to be completely in the dark about the nation's most notorious white supremacist organization.

"Just so you understand, I don't know anything about David Duke. OK? I don't know anything about what you're even talking about with white supremacy or white supremacists," Trump said in response to a reporter's question on CNN about Duke's endorsement.

Trump knows Duke because he called him a "Klansman" in 2000.

He later blamed a "lousy earpiece" for his response, saying he couldn't understand what reporter Jake Tapper had asked him, though he clearly repeated David Duke's name in his response.

Le Pen's endorsement follows comments by former Mexican president Felipe Calderon, who compared Trump to Adolf Hitler.

"I think his logic of exalting white supremacy isn't even acting against immigration — Donald Trump is the descendant of migrants — it is acting and speaking against immigrants who have a different skin colour than him, which is frankly racist and is a bit like the exploitation of raw nerves that Hitler did in his day," Calderon told reporters in Mexico City.