President Trump told a crowd at a rally for Alabama candidate Sen. Luther Strange Luther Johnson StrangeSessions hits back at Trump days ahead of Alabama Senate runoff The biggest political upsets of the decade State 'certificate of need' laws need to go MORE (R) on Friday night that they should "pick up and leave" NFL games if they see players kneeling during the national anthem.

"When people like yourselves turn on television and you see those people taking the knee when they are playing our great national anthem — the only thing you could do better is if you see it, even if it's one player, leave the stadium," Trump suggested. "I guarantee things will stop."

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"Luther and I and everyone in this arena tonight are unified by the same great American values. We're proud of our country. We respect our flag," he continued.

"Wouldn't you love to see one of these NFL owners, when somebody disrespects our flag, to say, 'Get that son of a bitch off the field right now. He is fired,' " Trump said.

Trump has previously blasted NFL player Colin Kaepernick, who gained notoriety after he knelt during the national anthem to protest the treatment of people of color in the U.S.

The president slammed Kaepernick earlier this year, saying he is a free agent because of his refusal to stand during the national anthem.