Former Massachusetts Gov. Bill Weld, who is challenging President Trump in the Republican primaries, proclaimed Monday that the president committed treason through his controversial phone call to Ukrainian President Volodymyr Zelensky -- adding that the punishment for treason is death.

The statement drew a swift rebuke from the Trump campaign.

“The media’s affliction with Trump Derangement Syndrome has driven them into an actual discussion of the proposed execution of the President of the United States,” communications director Tim Murtaugh told Fox News. “In severe cases of TDS such as this, immediate consultation with a physician is recommended.”

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Weld was responding to claims that Trump pressured Zelensky to investigate Hunter Biden -- the son of former vice president and current Democratic presidential candidate Joe Biden -- and threatened to withhold military aid to Ukraine as leverage. Trump has denied wrongdoing.

“Talk about pressuring a foreign country to interfere with and control a U.S. election, it couldn’t be clearer. And that’s not just undermining democratic institutions, that is treason," Weld said on MSNBC's "Morning Joe." "It’s treason pure and simple. And the penalty for treason under the U.S. Code is death. That’s the only penalty.”

Weld then referred to impeachment as a possible alternative to a criminal case, stating, “The penalty under the Constitution is removal from office, and that might look like a pretty good alternative to the president if he could work out a plea deal.”

Weld’s mention of the death penalty later ignited a conversation about the “legal framework” of the claim. Weld again said, “The only penalty for treason is death, it’s spelled out in the statute.”

While the U.S. Code does list the death penalty as a punishment for treason, Weld’s claim that it is the only penalty is false. Treason is covered by 18. U.S. Code § 2381, which says that a person guilty of treason “shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States.”

When Fox News asked Weld’s campaign about this, they did not immediately respond.

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Weld's comments came during a joint television appearance with the two other longshot Republicans challenging Trump in next year's primary: former South Carolina governor and congressman Mark Sanford and former Illinois Rep. Joe Walsh. They have joined together to protest the canceling of GOP presidential primaries in some states in 2020.