Sen. Lamar Alexander, who cast a critical vote in the Senate trial against calling witnesses to testify, said he will support acquitting President Trump because impeachment would allow partisanship to run rampant in the chamber.

“I’m going to vote to acquit. I’m very concerned about any action that we could take that would establish a perpetual impeachment in the House of Representatives whenever the House was a different party than the president. That would immobilize the Senate,” the Tennessee Republican said during an interview with NBC’s “Meet the Press” that aired Sunday.

“You know, we have to take those articles, stop what we’re doing, sit in our chairs for 11 hours a day for three or four weeks, and consider it. And it would immobilize the presidency,” he continued. “So I don’t think want a situation, and the framers didn’t either, where a, where a partisan majority in the House of either party can stop the government.”

Alexander, who is retiring from the Senate at the end of this year, said it should be up to American voters to decide Trump’s fate in November.

“The people. The people is my conclusion,” Alexander said when asked who should determine if Trump crossed the line in his dealings with Ukraine. “You know, it struck me, really for the first time, early last week, that we’re not just being asked to remove the president from office. We’re saying, ‘Tell him he can’t run in the 2020 election which begins Monday in Iowa.’”

Democrats had hoped that Alexander would be one of four Republican senators they needed to vote with them to vote to allow witnesses to testify at the Senate trial.

But the 79-year-old senator said while Trump’s actions were inappropriate, they weren’t impeachable.

He stood by that decision.

“If you have eight witnesses who say someone left the scene of an accident, why do you need nine? I mean, the question for me was: Do I need more evidence to conclude that the president did what he did? And I concluded no,” Alexander said.

He said he believes Trump did two things – he called on Ukraine’s president to investigate former Vice President Joe Biden and used nearly $400 million in military aid as motive to launch the probe.

“Those are the two things he did. I think he shouldn’t have done it. I think it was wrong. Inappropriate was the way I’d say – improper, crossing the line,” Alexander said.

The Republican-controlled Senate voted 51-49 to defeat the Democrats’ bid to hear witnesses in the Senate trial, paving the way for this Wednesday’s scheduled vote on acquittal.

Sen. Mitt Romney of Utah and Susan Collins of Maine were the only two Republicans who voted in favor of witnesses.