WEST LAFAYETTE, Ind. -- Jim Harbaugh shot back at the U.S. president Saturday night for suggesting that a boycott of the NFL over players who kneel during the national anthem.

Asked by a reporter after Michigan's 28-10 win over Purdue, Harbaugh called the comments made by Donald Trump Friday night in Alabama "ridiculous."

The Michigan coach even offered up a suggestion to Trump, whom he once complimented for being anti-establishment.

"No, I don't agree with the president," Harbaugh said. "Listen, that's ridiculous. Check the Constitution."

Trump was speaking at a campaign rally for Alabama Sen. Luther Strange, a Republican who supported the president in his 2016 bid for presidency.

"Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a (expletive) off field the right now, out, he's fired. He's fired!'" Trump told an energetic crowd in Huntsville.

"You know, some owner is going to do that. He's going to say, 'That guy disrespects our flag, he's fired.'"

The president's comments have since drawn wide-spread criticism from the NFL and its Players Association, with both groups coming out Saturday in support of the players.

In a statement, NFLPA Executive Director DeMaurice Smith reminded everyone of the players' free-speech rights as Americans.

"This expression of speech has generated thoughtful discussions in our locker rooms and in board rooms," Smith said. "However, the line that marks the balance between the rights of every citizen in our great country gets crossed when someone is told to just "shut up and play."

So why Harbaugh? Well, he coached former San Francisco 49ers quarterback Colin Kaepernick, the one responsible for this controversy after he kneeled for the Star-Spangled Banner last summer.

Harbaugh has supported Kaepernick ever since, even writing an endorsement for the ex-NFL player's entry in TIME Magazine's 100 Most Influential People in 2017.

"I thank Colin for all he has contributed to the game of football as an outstanding player and trusted teammate," Harbaugh wrote.

"I also applaud Colin for the courage he has demonstrated in exercising his guaranteed right of free speech. His willingness to take a position at personal cost is now part of our American story."