A US billionaire has launched a campaign, calling for the impeachment of “mentally unstable” President Donald Trump, who has brought America “to the brink of nuclear war.”

Tom Steyer, an American billionaire and self-identified environmentalist addressed the public in a video released on Thursday. “He [Donald Trump] has brought us to the brink of nuclear war,” the tycoon said.

Steyer lambasted the current administration of the US leader as well as Congress, saying people there know that Trump “is a clear and present danger, who's mentally unstable and armed with nuclear weapons, and they do nothing.”

“If that isn't a case for impeaching and removing a dangerous president, then what has our government become?” he asks. The billionaire explained that he is funding the effort “to demand that elected officials take a stand” on impeaching Trump.

In an open letter, Steyer goes on to say that Trump is simply lacking “fitness for office,” and notes that the question of impeachment thus “becomes a very real issue.”

READ MORE: US porn king offers $10mn for ‘smoking gun’ to impeach Trump

Steyer is the founder of Farallon Capital investment firm and NextGen America environmental political action committee which opposes the controversial Keystone XL pipeline.

Earlier in October ‘porn king’ Larry Flynt offered a hefty sum of up to $10 million for any information that would help to remove Donald Trump, whom he called “a moron” from the White House.

“Larry Flynt and Hustler magazine announce a cash offer of up to $10 million for information leading to the impeachment and removal from office of Donald J. Trump,” an advertisement from the founder of the Hustler pornographic magazine said.