Billionaire Bill Gates denounced Sen. Elizabeth Warren’s wealth tax plan Wednesday, Nov. 7, and hinted at a possibility of voting for President Donald Trump in 2020.

“If I had to pay $20 billion, it’s fine,” Gates said during a New York Times DealBook conference. “But when you say I should pay $100 billion, then I’m starting to do a little math about what I have left over.” He added that he was “just kidding” when the crowd laughed.

Warren proposed her progressive wealth tax dubbed “Ultra-Millionaire tax,” saying “It’s time for the rich to pay their fair share.” The plan would apply a 2% tax on every dollar of net worth for households worth $50 million or more, and a 3% tax on every dollar of net worth beyond $1 billion, which would impact approximately 75,000 households and raise $2.75 trillion over a decade, the campaign said.

“I’m not going to make political declarations,” Gates said. “But I do think no matter what policy somebody has in mind […] whoever I decide will have the more professional approach in the current situation, probably is the thing I will weigh the most. And I hope that the more professional candidate is an electable candidate.”

“I’m not sure how open-minded she is, or that she’d even be willing to sit down with somebody who has large amounts of money,” he added.

Warren said that she “would love” to meet with the Microsoft founder to discuss her wealth tax.

Another top-tier Democratic presidential candidate Sen. Bernie Sanders who has embraced Warren’s idea, goes further with his proposal for a wealth tax titled “The Tax on Extreme Wealth” that his campaign claimed would cut the wealth of billionaires in half over 15 years. 

“I don’t think that billionaires should exist,” Sanders said in an interview with The New York Times. “This proposal does not eliminate billionaires, but it eliminates a lot of the wealth that billionaires have, and I think that’s exactly what we should be doing.”