WGA East president and House of Cards creator Beau Willimon went off on President Donald Trump today, calling the Commander-in-Chief “treasonous.”

Willimon issued a long and rancorous tweetstorm today, bitterly attacking Trump and social media outlets over the course of several hours.

His Trump comments were made in response to a tweet by Sen. John McCain, who said, “To our allies: bipartisan majorities of Americans remain pro-free trade, pro-globalization & supportive of alliances based on 70 years of shared values. Americans stand with you, even if our president doesn’t.” The Arizona Senator is currently suffering from brain cancer but has refused to resign his post.

But Willimon, a frequent critic of the president, went one step farther: “Until the Congress is willing to use its constitutionally mandated power to end this presidency due to its rampant corruption and treasonous behavior, the damage will continue. Only actions, not statements, can stop it.”

Earlier in the day, responding to the fallout from Trump’s meeting with the G-7 in Canada, Willimon tweeted that “Trump has stupidly & dangerously succeeded in alienating our greatest allies. They now find solidarity in opposing us. Meanwhile he disparages Canada while praising North Korea & Russia. Dictatorships are, by nature, enemies of people. Trump is making us an enemy of the world.”

“Trump,” he tweeted, “is proving to be the most effective ambassador Russia has ever sent to Washington.”