Former Massachusetts Gov. Bill Weld, who is challenging President Donald Trump for the Republican nomination next year, accused the president of “treason” for pressing the leader of Ukraine to investigate former vice president Joe Biden and his son.

After suspending $250 million in military aid to Ukraine, Trump repeatedly pressured Ukrainian President Volodymyr Zelensky to investigate Biden and his son, Hunter, Weld said.

“Talk about pressuring a foreign country to interfere with and control a U.S. election,” Weld said during an appearance on MSNBC’s “Morning Joe” on Monday. “It couldn’t be clearer, and 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.”

He added, “The penalty under the Constitution is removal from office and that might look like a pretty good alternative to the president if he can work out a plea deal.”

Weld noted that the Constitution calls for the removal of presidents for “treason, bribery or other high crimes and misdemeanors” and argued that Trump has now met the most serious threshold.

“We don’t have to worry about bribery any more, although I think he’s committed that,” Weld said. “We don’t have to worry about other high crimes and misdemeanors, although I think he’s committed many. He’s such a lawless man. We’ve got treason, and we don’t have to dribble around the court. We can go right for the hoop.”

“It’s well past time for this guy, in my opinion to be colloquial, to be carted off to save us all,” said Weld, adding that Trump had no respect or understanding of the law.

Weld’s comments come a day after another former Massachusetts governor, Mitt Romney, said it “would be troubling in the extreme” if Trump pressured Ukraine’s president to investigate a political rival before the 2020 election.

In a tweet, Romney, who was the GOP’s presidential nominee in 2012 and now a U.S. senator from Utah, also said it was “critical” for the facts surrounding the Zelensky call to emerge.

“If the President asked or pressured Ukraine’s president to investigate his political rival, either directly or through his personal attorney, it would be troubling in the extreme. Critical for the facts to come out,” Romney tweeted.

Trump on Sunday hinted he mentioned Joe and Hunter Biden in the phone call with Zelensky — though the president insisted he has done nothing improper.

The call with Zelensky is part of a whistleblower complaint that the acting director of national intelligence, Joseph Maguire, has been unwilling to turn over to Congress — a refusal that has angered Democrats.