One of Donald Trump’s leading candidates for vice president, Newt Gingrich, was recorded earlier this year telling fellow Republicans that he didn’t think Trump was a real conservative and speaks to his supporters “at the lowest level of any candidate in either party.”

Gingrich also expressed concern of how Trump would make the move from campaigning to governing:  “How we make the transition from, you know, language for fourth graders to real policy, I don’t know.”

ProPublica reviewed the previously unreleased recording of the speech that was made in February in Washington to the Republican State Leadership Committee which displayed Gingrich’s mixed admiration for Trump’s success.

“This is not a guy who’s shallow or simple, but he is a guy who knows an immense amount about marketing, which is why he talks at a fourth-grade level. He talks at the lowest level of any candidate in either party, not because he’s stupid,” Gingrich said. “He does it because he knows if you talk at a fourth-grade level everybody can understand you.”

Gingrich, who didn’t endorse Trump until May, is now considered to be on the short list to be Trump’s running mate. However, Gingrich admitted in his February speech that he was clueless of what type of president Trump would be.

“I do not believe anybody including Trump can tell you what a Trump presidency would be like,” Gingrich said.

Gingrich spent close to ten minutes discussing Trump during his half hour speech and showed a mix of amazement and judgement, comparing his approach to “some weird combination of the Kardashians. I mean think about it, the whole tweeting, the whole continuous noise.”

Gingrich lauded the presumptive Republican nominee’s abilities in politics and business as well his skill to effectively destroy his rivals: “He’s the grizzly bear in the room. He’s not normal.”

Gingrich said Trump “has found a formula which is worthy of study. I operate on the premise that when people are doing something really smart, even if I don’t like it or I don’t understand it, it’s my job to figure them out, not their job to figure me out.”