White supremacist David Duke reportedly balked at endorsing Donald Trump last year because he believed the Republican presidential candidate was too friendly with the Jews.

Now that Trump is the GOP front-runner, Duke has changed his tune — and experts say he is trying to ride that bandwagon back into the good graces of those who once looked to him for leadership.

“David Duke still portrays himself as a white nationalist hero, but the fact is he hasn’t done anything political in years,” Mark Potok of the Southern Poverty Law Center, a watchdog group that monitors racist groups, told NBC News on Monday. “Duke’s having a moment in the news now, and he needs this. In the white supremacist world, he’s seen as an opportunist, someone who is living off the movement.”

Marilyn Mayo of the Anti-Defamation League, which has also kept close tabs on Duke for many years, said Trump has done something Duke has been unable to do, which is “energize the white supremacist movement.”

“They don’t see Trump as a white nationalist, but he is mainstreaming some of the issues they hold dear, like keeping Mexicans and Muslims out of the country,” said Mayo. “He’s become a voice for some of their views.”

There was no immediate response to an email for comment sent to Duke’s website, on which he refers to himself as “Dr. David Duke.” He was awarded a doctorate in history in 2005 from a private Ukrainian university that has been accused of fomenting anti-Semitism.

But in an August 2015 interview with The Daily Beast, Duke said he worried that Trump would not do anything about the “Jewish elite” supposedly running the country.

“Trump has made it very clear that he’s 1,000 percent dedicated to Israel, so how much is left over for America?” Duke said.

Image: David Duke

Image: David Duke

Trump, for his part, told Bloomberg News he would never accept an endorsement from Duke. But on Sunday, in an interview with CNN’s Jake Tapper, Trump claimed not to know anything about Duke.

Duke, 65, first made his racist mark at Louisiana State University back in 1970 when he founded the White Youth Alliance. He became infamous for parading on campus in a Nazi uniform.

Later, Duke became a Ku Klux Klan grand wizard, and soon replaced the white sheets with business suits in a bid to make the KKK more mainstream. He reached out to women and encouraged Catholics to join. He insisted the group was “pro-white” and “pro-Christian” — not anti-black.

In the meantime, Duke’s marriage to Chloe Hardin — with whom he had two daughters — fell apart. She went on to marry a neo-Nazi named Don Black, the founder of the racist website Stormfront.

Duke used the KKK as a springboard in 1989 to win a seat in the Louisiana legislature as a Republican, over the objections of the mainstream GOP, which lined up against him. It was the first and last time Duke won an election.

What followed were failed campaigns for governor, for senate — even the White House.

Meanwhile, Duke abandoned the Klan and formed the National Association for the Advancement of White People to press his racist agenda.

But Duke’s credibility in the racist ranks took a hit in 2002 when he was convicted of filing a false tax return and sentenced to 15 months in prison. Duke claimed he was being persecuted by the federal government. It turned out he was using donations from followers to fund his lifestyle and support a gambling habit.

Black blamed Duke’s legal problems on the usual culprit — the Jews.