Tom Steyer, a billionaire liberal who donated $91 million toward supporting Democrats in the 2016 election, has launched an all-out campaign to impeach President Donald Trump. He released his first TV ad yesterday in which he makes the case for "impeaching and removing a dangerous president."

"He's brought us to the brink of nuclear war, obstructed justice at the FBI, and in direct violation of the constitution, he's taken money from foreign governments and threatened to shut down news organizations that report the truth," Steyer says in the ad. "A Republican Congress once impeached a president for far less. Yet today, people in Congress and his own administration know that this president is a clear and present danger who is mentally unstable and armed with nuclear weapons—and they do nothing."

The ad links to the website NeedToImpeach, where Steyer lays out more grounds for impeachment and implores people to sign a petition against Trump.

While Steyer's campaign might seem like a pie-in-the-sky idea, his influence over the Democratic party shouldn't be underestimated—according to the Times, Steyer was the single biggest liberal donor in the last two federal elections (his pet issue before now has been climate change). In a letter to Democratic congressional offices and the party’s House and Senate campaign committees, Steyer implied that any candidates who want money will have to sign onto his campaign.

"This is not just an issue of Twitter screeds but what it means for a person who has control over our nuclear arsenal," Steyer, a California-based hedge fund investor, said in the letter. "I hope you will make your position clear so that Democratic voters who are under constant attack by this administration, know their elected representatives have the patriotism and political courage to stand up and take action."

Thus far, most Democrats have been reluctant to formally push for impeachment, with party leaders urging the rank-and-file to await the results of Special Counsel Robert Mueller's investigation into whether the Trump campaign colluded with Russia to swing the election. California Representative Adam B. Schiff noted back in May, "No one ought to, in my view, rush to embrace the most extraordinary remedy that involves the removal of the president from office." As recently as September, a network of progressive groups (including MoveOn.org, Stand Up America, American Bridge and End Citizens United), advised elected officials to not "invoke impeachment," though there have been a few—including California Rep. Brad Sherman and Texas Rep. Al Green—who have forged ahead anyway.