Wall Street hasn’t held back as far as how much it absolutely hates the idea of an Elizabeth Warren presidency, mostly in regard to her wealth tax and anti-big business plans, and now Microsoft founder and CEO Bill Gates is stepping into the fray.

Gates, who in the past has criticized President Donald Trump, could end up backing the incumbent if Sen. Elizabeth Warren is the Democratic Party’s nominee for the presidency. At the crux of Gates’ complaint with Warren is her proposed wealth tax, which would cost Gates what would be a massive fortune to anyone but himself and a few other members of the Forbes 400. Gates checks in at No. 2 on the list of wealthiest Americans with more than $106 billion dollars to his name.

“If I had to pay $20 billion, it’s fine,” Gates said. “But when you say I should pay $100 billion, then I’m starting to do a little math about what I have left over.”

Warren’s proposed wealth tax wouldn’t cost him $100 billion and even if it did, he’d still have nearly $10 billion left, but it would obviously still be a massive government confiscation of the wealth he’s earned since founding the world’s largest computer software company.

The wealth tax Warren has proposed would tax fortunes above $50 million at 2%, and tax wealth above $1 billion at 3%. The tax would bring in about $2.75 trillion a year to pay for a number of social programs and giveaways to combat wealth inequality, according to Warren.

Gates said he is in favor of progressive taxation and is open to paying more, saying he will ultimately vote for who is the most “professional.”

“I’m not going to make political declarations,” he 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.”

Gates also said he doubts Warren is open-minded enough — which could be what he meant by “more professional” — to change her position on her extreme wealth taxes. In fact, she recently said she’d be happy to double her wealth tax to help pay for Medicare for All.

“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,” Gates said.

Warren, who isn’t taking campaign donations from big corporations, said she’d be happy to sit down with Gates to discuss her wealth tax plan.