(CNN) President Donald Trump's pick to serve on the Federal Reserve Stephen Moore once criticized Trump's positions on immigration, describing them as "extreme nativist" and calling them "crazy" and "dangerous."

Moore made the comments in an August 2015 radio interview with Larry Kudlow, who now serves as the President's top economic adviser. In that interview, Kudlow compared Trump's immigration plans to the worst parts of World War II -- in an apparent reference to the Holocaust -- and said Trump's only real supporters came from "the nativist fringe."

In a statement to CNN, Kudlow said he should have never made the comments about Trump's immigration proposal.

"I should've never said it because it was never true. President Trump is actually trying like hell to fix an immigration system that's been broken for 40 years -- hurting American workers, acting as a drain on our economy -- and he's the only one with the guts to call it out and fix it," he said.

Moore told CNN on Monday that he said "a lot of negative things about Donald Trump before I met him."

Kudlow and Moore eventually supported Trump in his 2016 bid for the White House, serving as economic advisers to his presidential campaign. Moore's past criticism of the President is coming to light as his prior views and statements face scrutiny ahead of what could be a contentious confirmation process to the Federal Reserve Board of Governors. Trump said in March he intends to nominate Moore to the position, but Moore has not officially been nominated yet.

Just last week, Moore told CNN's Erin Burnett he no longer supported a gold standard and in emails told CNN's KFile he no longer wanted to abolish the Federal Reserve or not have a federal minimum wage, positions he had previously espoused.

In the August 2015 radio interview, Kudlow said "Donald Trump and his policies are doing damage to the stock market." Kudlow added, "This is nuts. This is crazy stuff. This is crazy, crazy stuff." (Kudlow told CNN in a statement on Monday that this comment was "simply speculative radio chatter that turned out to be wildly inaccurate because it was based on misunderstandings, misinterpretations, and misreads of then-candidate Trump's actual policies.")

Trump at the time laid out a policy proposal on immigration that would put stricter laws in place related to legal immigration and overturn laws granting citizenship those born in the United States. He repeatedly called for deporting undocumented immigrants in the United States.

In questioning Moore, Kudlow called Trump's deportation plans "shocked a lot of people" adding that Trump's "only real supporters" were "the nativist fringe."

Moore responded, saying, "I think it's a crazy policy. I think it's bad economics and I think it's even worse politics. And how many times do Republicans have to lose elections before they realize that if they really want to get Asian voters, and if they want to get Latino voters -- and as a free market conservative, I want those. I think that those voters should be voting with us, Larry. But with this very extreme nativist position that says, 'we just don't want people that look like you and talk like you and act like you.' It's going to turn those voters into permanent Democrats. The Wall Street Journal put this very well. In the 1920s when the Republicans turned down immigration, they lost ethnic voters for generations to come. So it's a very dangerous thing."

"It's terrible economics because immigrants who come to this country to work, those are the people we want," added Moore. "I'm with him when he says that we shouldn't let him immigrants get welfare. But the vast majority of immigrants come to this country because they want a job, because they want economic opportunity. They want to share on our freedoms. And that's what America's all about."

Twice in the show, Kudlow called Trump's various comments on deportation "un-American," and said they reminded him of the worst parts of World War II.

"Jumping right into deportation of illegals, 11 or 12 million people, which I'm just going to tell you my opinion, it's an un-American," Kudlow said. "What is this? Taking police and going house to house? I hate to say it, but what does that reminds us of. What does that reminds us of? It reminds us of the worst parts of World War II. What the hell is that? That's not America. That's not your America. That's not my America. I'm the -- whatever. I am third generation from immigrants. That's not America. No. I mean it's just crazy."

Kudlow repeated the comments when speaking with Moore.

"Somebody has to stand up at a debate and say, you are completely wrong about mass deportation," he said. "That is un-American. It's smacks by the way of the worst things that we read about in World War II. On the other hand, the rest of us can coalesce around a good strong position to strengthen our legal immigration situation and stop the law-breaking. Who's going to stand up and say that?"