Sen. Bill Cassidy is facing a broadside from his state’s political party for his decision to change positions and vote to call former President Donald Trump’s impeachment trial constitutional.

In a statement released Tuesday, just hours after Cassidy (R-La.) opted in a last-minute decision to vote with the Democrats, the Louisiana GOP said it was “profoundly disappointed” by the senator’s vote, referring to the former commander-in-chief as a “private citizen.”

“We feel that an impeachment trial of a private citizen is not only an unconstitutional act, but also an attack on the very foundation of American democracy, which will have far reaching and unforeseen consequences for our republic,” the statement read.

“We also remind all Americans that former President Trump is innocent of the politically motivated, bogus charges now pending against him in a kangaroo court presided over by an openly hostile political opponent,” it continued.

“How far justice has fallen in the short time that Democrats have been in control of the federal government!” the statement closed.

A rep for Cassidy could not immediately be reached by The Post for response to the state party’s condemnation.

Asked Wednesday if he stood by his vote after the rebuke, Cassidy said yes.

“The issue was, is it constitutional? And at the end of the day, clearly it had been established that it is constitutional,” he said.

In reaction to lead Trump defense attorney Bruce Castor’s performance Tuesday, the Louisiana senator said he changed his position on the matter of constitutionality.

During Tuesday’s arguments, Castor discussed the fall of ancient governments in Rome and Greece, mistakenly referred to himself as the “lead prosecutor,” and barely addressed the case against the former president.

His handling of the proceedings was panned on both sides of the Senate aisle, but Cassidy was the only lawmaker to change his position on the issue as a result.

Speaking to reporters after the vote Tuesday, Cassidy slammed Castor and fellow lead defense attorney David Schoen’s presentation.

“They did everything they could but to talk about the question at hand, and when they talked about it, they kind of glided over it, almost as if they were embarrassed of their arguments,” the GOP lawmaker said.

“Now, I’m an impartial juror, and one side is doing a great job, and the other side is doing a terrible job on the issue at hand. As an impartial juror, I’m going to vote for the side that did the good job.”

Asked why the former president’s team missed the mark, Cassidy responded with a rhetorical question of his own: “Did you listen to it?”

“It speaks for itself. It was disorganized, random, had nothing — they talked about many things, but they didn’t talk about the issue at hand,” he continued.

The senator also revealed that at one point, he leaned over to Sen. Ted Cruz (R-Texas) to ask if Trump’s team was even talking about the issue at hand: the constitutionality of impeaching a former president.

“[Cruz] goes, ‘Not now,'” Cassidy said. “I’m thinking maybe I’m missing something.”