WASHINGTON – Former Massachusetts Governor and Republican presidential candidate Bill Weld slammed President Donald Trump's contacts with the government of Ukraine in a television interview on Monday morning, calling Trump's actions "treason."

"Talk about pressuring a foreign country to interfere with and control a U.S. election. That's not just undermining democratic institutions. That is treason. It's treason pure and simple, and the penalty for treason under the U.S. code is death. That’s the only penalty," Weld said, speaking on MSNBC's "Morning Joe."

"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," he added.

Trump has sparked controversy amid questions about his alleged pressuring of the Ukrainian government to investigate former Vice President Joe Biden's son Hunter Biden. On Sunday, Trump acknowledged having a conversation with the Ukranian president about Biden but said their conversation was appropriate.

Journalist Andrew Feinberg pointed out that what Trump is accused of doing with the Ukranian government was likely not treason under the U.S. code, as an act of treason would require the United States to be engaged in war or actively aiding an enemy.

Weld had been part of a panel of Republicans including former Reps. Mark Sanford, R-S.C., and Joe Walsh, R-Ill who sought to challenge Trump in the 2020 primaries.

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The three challengers face long odds in their quest to challenge Trump. Several state Republican Parties have canceled their primaries in 2020 in an effort to support Trump and avoid controversy in the nomination process, and Trump's approval rating among Republicans was about 91% in a recent Gallup poll.