Democrat mega-donor and California billionaire Tom Steyer announced a $10 million national advertising campaign Friday in which he calls for President Trump’s impeachment.

In the ad called “Join Us,” Steyer argues that Trump is unfit for office because he has pushed the U.S. toward nuclear war, threatened the shutdown of news organizations he does not like, accepted money from foreign governments, and obstructed justice at the FBI.

“People in Congress and his own administration know this president is a clear and present danger who is mentally unstable and armed with nuclear weapons,” Steyer, who bills himself as an “American citizen,” says in the ad. “And they do nothing.”

He urges those who watch his ad to contact members of Congress and demand they bring up articles of impeachment.

CBS San Francisco reports that Steyer planned to spend eight-figure sums of money on the ads but declined to specify the exact amount.

Steyer is considering the investment as he weighs running against incumbent U.S. Sen. Dianne Feinstein (D-CA) in the 2018 Democratic primaries.

The billionaire added that he would spend an additional seven-figure sum on a related ad campaign.

Steyer reportedly dropped $87 million on the 2016 elections and poured millions of dollars into his NextGen Climate Action group to combat global warming.

He has also funded a ballot measure to raise taxes on cigarettes in California and bankrolled an ad campaign attempting to block Secretary of State Rex Tillerson’s nomination to Trump’s Cabinet.

Some members of Congress already jumped on the impeachment bandwagon long before Steyer launched his impeachment ad campaign.

Rep. Al Green (D-TX) began pushing for Trump’s impeachment in May, becoming one of the first members of Congress to offer to bring up articles of impeachment that would start the process. His impeachment resolution died before it came up for a vote, but he vowed to bring up the articles again at a later date.