Democratic frontrunner and former Vice President Joe Biden doesn’t seem as concerned with the Ukraine scandal as he is with President Trump needing to release his tax returns.

During an interview on CBS’ “60 Minutes” Sunday night, Norah O’Donnell asked Biden if there was anything he wanted to say to the President. Biden repeated his call for the President to “release your tax returns or shut up.”

“Mr. President release your tax returns — let’s see how straight you are, OK? I put out 21 years of mine so show us your tax returns. What are you hiding?” Biden said. “You want to deal with corruption? Start to act like it. Release your tax returns or shut up.”

When asked about his thoughts on Trump repeatedly arguing that Russian interference in the 2016 election was a hoax, Biden called him an “idiot.”

“He’s an idiot in terms of saying that,” Biden said. “Everybody knows it. Nobody doubts it.”

Biden added that all he said to his son Hunter — who Trump also targeted in the now-infamous July phone call with Ukraine President Volodymyr Zelensky as part of his Ukraine pressure campaign to dig up false allegations on the Democratic frontrunner — was “I hope you know what you’re doing.”

“He’s a grown man. What I meant by that is I hope you thought this through, I hope you know exactly what you’re doing here,” Biden said, before insisting that he said “nothing more than that” because he never discussed his business with his sons or daughters. “I’ve never discussed [my business with] them because they know I have to do my job and that’s it. They have to make their own judgments.”

Earlier in the interview, Biden expressed his dissatisfaction with Facebook for refusing to remove the Trump campaign’s ad pushing the debunked conspiracy theory about him and Ukraine.

“Everyone knows ads by Trump are a flat lie,” Biden said. “I’m glad they brought the Russians down. Why not bring down the lies that Trump is telling and everybody knows they’re lies.”

Watch Biden’s interview on “60 Minutes” below: