Senator Ted Cruz is the latest to weigh in on the professional athletes who are refusing to stand for the American national anthem.
In a series of tweets, the Texas Republican called for a boycott of "rich spoiled athletes" who are "insulting" the US flag.
"To all the athletes who have made millions in America's freedom: stop insulting our flag, our nation, our heroes," Mr Cruz tweeted Monday in response to ESPN analyst Jalen Rose, who saluted the professional football players for protesting.
"Here's a peaceful protest," Mr Cruz continued, "never buy another shoe, shirt, or jersey of rich spoiled athletes who dishonour our flag."