San Francisco billionaire Tom Steyer running for president in 2020

July 9 (UPI) -- Billionaire Tom Steyer announced Tuesday he will run for president of the United States, joining a growing list of more than 20 candidates seeking the Democratic nomination in 2020.

Steyer is a former hedge fund manager and frequent Democratic donor in San Francisco who crusades against corporate money in politics. In a video posted to his Twitter account, Steyer said corporations driven by profits are corrupting the U.S. political system.

He blamed court decisions that have ruled that corporations are people, which leads to companies stopping progress and justice because it affects the bottom line.

"We've got to take the corporate control out of our politics," Steyer said. "All of these issues go away when you take away the paid opposition from corporations who make trillions of extra dollars by controlling our political system."

He was also the first major Democrat to call for President Donald Trump to be impeached.

Steyer stepped down from his investment firm in 2012 and pledged to donate half the wealth that he earns in his lifetime to worthwhile causes.

"We have a society that's very unequal and it's really important for people to understand that this society is connected," Steyer said.

He cited climate change as an example where companies are driven by profits rather than what's best for the planet. In 2013, he founded NextGen America, a nonprofit aimed at fighting climate change, promoting social justice and encourage participation in democracy.

"We'd rather make money than save the world," Steyer said.