United States president Donald Trump insists he will not watch the NFL or the US Soccer sides if players fail to stand for the national anthem.
The president has opposed kneeling during the anthem since former NFL star Colin Kaepernick took a knee in 2016 to highlight racial inequality.
The NFL and US Soccer have performed U-turns over the protests with both saying they were wrong not to listen amid ongoing protests following the death of George Floyd, an unarmed African American man who died in police custody.
Republican congressman Matt Gaetz criticised US Soccer's decision, made on Thursday, on social media, and Trump reacted by writing on Twitter: "I won't be watching much any more."
Trump added: "And it looks like the NFL is heading in that direction also, but not with me watching."
US Soccer introduced the ban in 2016 after Megan Rapinoe took a knee to support ex-San Francisco 49ers quarterback Kaepernick.
The NFL tried to ban kneeling during the anthem in May 2018 and introduced a new policy with teams fined if players failed to stand only to put the plan on hold two months later.