(CNN) President Donald Trump criticized some in the National Football League Friday night at a rally for Alabama Republican Senate candidate Luther Strange, saying team owners should fire players for taking a knee during the national anthem.

Trump added that if fans would "leave the stadium" when players kneel in protest during the national anthem, "I guarantee, things will stop."

Trump said NFL owners should respond to the players by saying, "Get that son of a bitch off the field right now, he's fired. He's fired!"

"For a week, (that owner would) be the most popular person in this country. Because that's a total disrespect of our heritage. That's a total disrespect for everything we stand for," Trump said.

Last year, Colin Kaepernick -- formerly with the San Francisco 49ers, but currently without a team -- drew national attention for refusing to stand during "The Star-Spangled Banner" prior to kickoff.

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