NASCAR truck racer Ray Ciccarelli intends to quit at the end of the season, after the series decided to ban Confederate flags at its events.
The Confederate flag has long been a symbol of racism and division in the United States, since it was adopted by pro-slavery southern states during the Civil War.
On Thursday (NZ time), NASCAR announced the flag could no longer fly at racetracks or any related properties.
The move comes amid global social unrest over the death of African-American George Floyd at the hands of white police officer Derek Chauvin last month.
Protests have rocked the nation for two weeks and Confederate monuments are being removed across the south - NASCAR's traditional fan base.
In a since-deleted Facebook post, Ciccarelli calls the move "political BS" and says he's leaving because of the decision.
"Well, it's been a fun ride and dream come true, but if this is the direction NASCAR is headed, we will not participate after the 2020 season is over," Ciccarelli writes on Facebook.
"I don't believe in kneeling during the anthem nor taking people's right to fly whatever flag they love.
"I could care less about the Confederate flag, but there are people that do and it doesn't make them a racist. All you are doing is f***king one group to cater to another.
"I ain't spending the money we are to participate in any political BS!! So everything is for SALE!!"
Ciccarelli has made 18 truck series starts over four seasons and has finished on the lead lap just one time, when he was ninth at Michigan in 2019.
NASCAR's only black driver, Bubba Wallace, called for a flag ban earlier this week and had 'Black Lives Matter' emblazoned on his car during Thursday's race at Martinsville, where he finished 11th.
He also wore a black 'I Can't Breathe' T-shirt, but did not kneel during the national anthem.
"That's a symbol of hate and it brings back so many bad memories," Wallace has told Good Morning America.
"There's no good that comes with that flag and that's the message we're trying to get across."