Longtime Democratic strategist James Carville warned that nominating Bernie Sanders to face President Donald Trump in the general election would be political suicide in an appearance on MSNBC Saturday.

Carville expressed fear on MSNBC that the media is not appraising voters of the risks of nominating Sanders, of whom he has been harshly critical.

“The entire theory that by expanding the electorate, increasing turnouts, you can win elections, is the equivalent of climate denying. When people say that, they are as stupid to a political scientist as a climate denier is to an atmospheric scientist,” he said.

Carville continued that he understood Sanders supporters who backed the Vermont Independent because of his platform.

But, he said, “If you’re voting for him because you think he’ll win the election, because he’ll galvanize heretofore sleepy parts of an electorate, then politically, you’re a fool.”

“And that’s just a fact,” Carville continued. “It’s no denying it, there’s so much political science, so much research on this that it’s not even a debatable question. And if people are appraised of this, and they know that, and they want to do it as Democrats, that’s their own business. But I don’t think they have all the facts that they need before they make this judgment going forward.”

“You’re describing a lot what sounds like political suicide?” MSNBC’s Nicolle Wallace said.

“It is,” Carville said.

Wallace proceeded to describe a Sanders win in MSNBC as “hitting the bottom.”

Watch above, via MSNBC.

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