A Colorado sporting goods store is closing after refusing to sell Nike merchandise in a protest against the company’s endorsement deal with former NFL player Colin Kaepernick.

Prime Time Sports, which had been in business for more than 20 years, decided to pull Nike products from its shelves after the company’s deal with Kaepernick to be the face of Nike’s 30th anniversary “Just Do It” advertising.

Owner Stephen Martin said his business struggled after the decision, and “just can’t keep the doors open anymore.”

“Being a sports store without Nike is kind of like being a milk store without milk or a gas station without gas. How do you do it? They have a monopoly on jerseys,” Martin told a local NBC station.

Kaepernick sparked a wave of protests by fellow NFL players in 2016 when he began kneeling during the national anthem to protest police brutality and racial inequality.

Nike’s decision to feature Kaepernick in the ads was immediately controversial, with some customers boycotting the brand and even burning their merchandise. President Donald Trump and his conservative backers lashed out at the NFL protests, and Trump attacked Nike for featuring Kaepernick.

Believe in something. Even if it means sacrificing everything. #JustDoIt pic.twitter.com/x5TnU7Z51i — Colin Kaepernick (@Kaepernick7) September 5, 2018

Martin also canceled an autograph session with Denver Broncos linebacker Brandon Marshall after he became the third NFL player to kneel during the U.S. national anthem in 2016.

“As much as I hate to admit this, perhaps there are more Brandon Marshall and Colin Kaepernick supporters out there than I realized,” the store owner lamented.

Martin, his store out of business, said he doesn’t regret his decision.

“I didn’t give in to big Nike and big dollars. I didn’t give in. I did it my way,” he said. “That part of the military respect that’s in me just cannot be sacrificed or compromised, as I believe Brandon Marshall and Colin Kaepernick both did. I don’t like losing a business over it, but I rather be able to live with myself.”

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This article originally appeared on HuffPost.