In a Monday interview on Boston Public Radio, constitutional law expert Laurence Tribe said the coming Senate impeachment trial of former President Donald Trump will be “completely devastating for the country to watch” and predicted that a handful of Trump’s Republican supporters in the Senate will be “shaken” toward a conviction vote.

"I believe that the presentations will be spell-binding, and I believe they will be terrifying,” he said.

The Senate impeachment trial is scheduled to begin Tuesday. Should all Democrats vote to convict Trump, a total of 17 Republicans will need to cross party lines to meet the two-thirds threshold for a full conviction. Currently, only a handful of Senate Republicans are expected to side with Democrats.

Read More: More Than A Month Later, It's Still January 6 On Capitol Hill

At the moment, the two dominant Republican arguments against conviction are that the Constitution doesn’t allow for the impeachment of a president who’s already left office and that Trump’s call for supporters to “fight like hell” on Jan. 6 falls under First Amendment protections. The Harvard Law School professor emeritus, however, said neither of those arguments hold much water.

"There are almost no serious people saying that the Senate doesn’t have the power” to convict Trump, he said.

To the question of whether the president’s calls to action consititute protected speech, Tribe cited the oft-used example of shouting “fire” in a crowded theater.

"The usual trope in First Amendment law is you can inform people there’s a fire in a crowded theater if there really is one. But if you yell ‘fire' in a crowded theater when there is no fire and cause a panic, you’re not protected by free speech,” he explained.

He continued, “this is worse than just yelling fire in a crowded theater. It’s like being the fire chief and watching while the mob starts to set fire to the crowded theater, and saying, 'Go to it, guys, go to it — you’ll lose your country if you don’t take it over.’ That’s what he did.”

Because of the apparent flimsiness of the pro-Trump defense, Tribe said he expects that a number of Republican senators, including some who’ve defended the former president up until now, will support conviction as impeachment proceedings unfold.

"The common trope, the conventional wisdom, that they’re just going through the motions, I think is dead wrong,” he said. "I’m not predicting that these senators, many of whom have shown themselves to be spineless … will do their duty under the Constitution. But some of them will, and those who don’t will pay the price in history."

Read More: The Big Lie At The Center Of The Impeachment Trial Is All About Black Voters

But Tribe was also clear that a Senate conviction alone won't be enough to prevent Trump from holding federal office in the future and said additional votes would need to take place, in addition to a Senate conviction, to effectively barr Trump from serving in the U.S. government in the years to come.

"There are some hard questions in the Consistution," Tribe ultimately concluded. "These are not among them."