In January, a few thousand mental health professionals, led by John Gartner, organized a Facebook petition warning that Donald Trump is psychologically incapable of competently discharging the duties of President of the United States. By April, the group, Duty to Warn, at a conference at Yale, agreed that the issue no longer was whether Trump is mentally ill but whether he’s dangerous. This week, Duty to Warn, now 63,000 signatories strong, not only broadcast that message in a wildly successful book—The Dangerous Case of Donald Trump: 27 Psychiatrists and Mental Health Experts Assess a President, edited by Bandy X. Lee, M.D., debuted near the top of The New York Times best-seller list—but became a political action committee (PAC).

The first is to “get the nuclear gun out of Trump’s hands,” by backing H.R. 669, sponsored by Representative Ted Lieu of California, which would prohibit a nuclear strike against an enemy unless Congress first declared war.

The second is to find and win over the 19 Republicans needed for passage of the bill. That, Gartner adds, will enable his group to perfect a program for flipping the 24 seats needed to end Republican control of Congress in 2018 so that Trump can either be reined in or impeached.

The majority of the country now knows that Donald Trump is unfit and they’re terrified,” says Gartner. “We have to drive them to the polls.” He envisions mobilizing campaigns of letter-writing to legislators by constituents and—borrowing the view put forth by political psychologist Drew Westen that targeting the limbic system drives people to the polls—airing videos that “fear monger with the truth.” “Instead of scaring people about killer immigrants or sex rings in pizza parlors,” he aims to create videos for candidates that explain the peril posed by Trump’s mental state and “talk about ‘I’m going to keep your children alive.’”