Big & Rich singer John Rich found himself on the receiving end of a firestorm of debate after he turned to Twitter on Monday (Sept. 3) to react to the news that Nike has hired Colin Kaepernick as the face of a new advertising campaign.

Nike revealed a new ad spot on Monday for the 30th anniversary of its Just Do It campaign that features the former San Francisco 49ers quarterback, who created a national debate when he became the first player to take a knee during the national anthem during the 2016 NFL to protest social injustice — particularly police violence toward minority communities and shootings of unarmed black men. He has been at the center of intense controversy and debate ever since and has remained a free agent since the end of that season, and President Trump has repeatedly decried taking a knee both in his personal appearances and on Twitter.

The new ad features a picture of Kaepernick with the slogan, "Believe in something. Even if it means sacrificing everything."

Rich turned to Twitter on Monday to write, "Hey @Nike I guess you made @Kaepernick7 your new 'face' of the brand because you love the way his socks look with your shoes? @Reebok here we come," accompanying his sentiments with a picture of Kaepernick's socks, which feature cartoons of police officers with pig faces.

Twitter users turned out in force to comment on Rich's post, split along predictable partisan political lines, with many of his more conservative fans applauding his post, while others decried his ideas and openly mocked him in the comments. Rich spent several hours trading tweets with various Twitter users, sharing a picture of Big & Rich's soundman, who had cut the trademark Nike logo off of his socks, and warning darkly that the iconic shoe company's stock would plummet. He invited Twitter users who disagreed to unfollow him, and even traded personal insults with some. See the entire thread below.

Kaepernick has filed a lawsuit against the NFL for collusion, alleging that the league is conspiring to prevent him from playing due to his protests. The Hill reports that an arbitrator ruled last week that Kaepernick's lawsuit will be allowed to move forward to trial.

According to ESPN, Nike signed Kaepernick to an endorsement deal in 2011 and has retained him over the years.

"We believe Colin is one of the most inspirational athletes of this generation, who has leveraged the power of sport to help move the world forward," Gino Fisanotti, Nike's vice president of brand for North America, tells ESPN.