White House National Economic Council (NEC) Director Kevin Hassett said in a Monday interview that billionaire hedge fund investor Bill Ackman “should ease off the rhetoric” after he warned that President Trump’s tariffs could lead to a “self-induced, economic nuclear winter.”

In an interview Monday on Fox News Channel’s “Fox & Friends,” Hassett called the remarks by Ackman, who endorsed Trump for president last year, “completely irresponsible rhetoric.”

“I would urge everyone, especially Bill, to ease off the rhetoric a little bit,” Hassett said in the interview, in response to Ackman’s warning.

Hassett said most of the country’s GDP is not affected by Trump’s new sweeping tariffs, noting imports account for just 14 percent of the GOP, “so 86 percent of GDP is affected by the deregulation and the tax cuts and everything else.”

“Even if you think that there will be some negative effect from the trade side, that’s still a small share of GDP,” Hassett said. “And so the idea that it’s going to be a ‘nuclear winter,’ or something like that, is completely irresponsible rhetoric.”

Hassett maintained that he and others at the White House still think that “these economic responses are exaggerated by critics.”

Hassett’s interview comes after Ackman offered a stark warning about the risks of Trump’s tariffs, arguing they could cause the economy to collapse and could hurt Trump’s supporters the most, writing, “This is not what we voted for.”

Ackman argued that Trump should consider calling a “90-day time out” that would allow him to negotiate and solve “asymmetric tariff deals, and induce trillions of dollars of new investment in our country.”

If that doesn’t happen and instead the U.S. launches “economic nuclear war on every country in the world, business investment will grind to a halt, consumers will close their wallets and pocket books, and we will severely damage our reputation with the rest of the world that will take years and potentially decades to rehabilitate,” Ackman wrote.

“The President has an opportunity on Monday to call a time out and have the time to execute on fixing an unfair tariff system,” Ackman wrote. “Alternatively, we are heading for a self-induced, economic nuclear winter, and we should start hunkering down. May cooler heads prevail.”