Watch the ad calling for Trump's impeachment that a billionaire is spending more than $10 million on

Billionaire Democratic mega-donor Tom Steyer is spending over $10 million to run a national advertisement calling for Trump's impeachment. In 2016, he spent $65 million supporting Democrats and environmental causes, including Martin O'Malley.

Steyer is considering challenging Democratic Sen. Dianne Feinstein in California, he's also mulling a 2020 presidential run.

In the ad, Steyer calls Trump "a clear and present danger" who is "mentally unstable" and armed with nuclear weapons. Friday morning Trump attacked Steyer on Twitter calling him "wacky and totally unhinged."