By Scott Malone
BOSTON (Reuters) - U.S. President Donald Trump kept up his verbal battle with the National Football League over players who drop to one knee during the national anthem, saying on Monday their acts of protest had nothing to do with racism.
Dozens of NFL players, coaches and even some owners joined in silent protest at games on Sunday against Trump's call for owners to fire players who do not stand during the "Star-Spangled Banner."
"The issue of kneeling has nothing to do with race. It is about respect for our Country, Flag and National Anthem. NFL must respect this!" Trump said on Twitter.
Trump kicked off his battle with the largest-grossing U.S. professional sports league at a rally on Friday, when he said any protesting player was a "son of a bitch" who should be "fired."
He met with criticism from many corners of the sports world.
"The childishness, the gratuitous fear-mongering and race baiting has become so consistent that we almost expect it, the bar has been lowered so far," San Antonio Spurs Head Coach Gregg Popovich told reporters on Monday. "I had no idea that I lived in a country where the president would say something like that."
White House spokeswoman Sarah Huckabee Sanders said that anti-racism protests should not be directed at the flag.
"If the debate is really for them about police brutality, they should protest the officers on the field that are protecting them instead of the American flag," she said.
The controversy highlighted a deep political rift that Trump's election has exposed across American society.
Former San Francisco 49ers quarterback Colin Kaepernick began kneeling during the anthem in protest of police brutality and racial inequities last year. No NFL team has signed Kaepernick for this season.
Not all players joined in Sunday's protests. Notably, Pittsburgh Steelers lineman Alejandro Villanueva, a U.S. Army veteran, stood alone at the entrance to the stadium for the anthem on Sunday while his teammates waited in the locker room.
Villanueva jerseys and other apparel have outsold those of all other players in the past 24 hours, said a spokesman for online retailer Fanatics, which operates NFLShop.com.
Villanueva's teammate, Ben Roethlisberger, on Monday said he regretted having missed the anthem.
"I was unable to sleep last night," Roethlisberger said in a statement. "I personally don't believe the Anthem is ever the time to make any type of protest."
The next test of NFL sentiment comes in Phoenix, Arizona, when the Cardinals host the Dallas Cowboys at 8:30 p.m. EDT (0030 GMT). Neither team has had a player conspicuously kneel during the anthem.
Cowboys owner Jerry Jones has expressed pride that his team has not joined in anthem protests, last month calling other athletes' actions "really disappointing."
Trump called for a boycott of games. Early reports from the major networks were mixed.
CBS Corp said overall viewership of games it broadcast on Sunday was up 4 percent from last year and 1 percent from last week.
NBC, owned by Comcast Corp, said viewership for its Sunday night game was down compared with the prior week.
Nike Inc said it supported athletes who had taken part in the protests.
"Nike supports athletes and their right to freedom of expression on issues that are of great importance to our society," the athletic wear maker said in a statement.
The debate attracted intense attention online, with the hashtag "#TakeAKnee" racking up 2.4 million mentions and "#TakeTheKnee" used 1.2 million times by Monday, while "#BoycottNFL" had 101,500 mentions.
Prominent players continued to speak out against Trump on Monday.
New England Patriots quarterback Tom Brady, who has said he considers Trump a friend, on Monday said he disagreed with Trump's remarks.
"I thought it was just divisive," Brady told Boston's WEEI radio.
At the same time as he berated the NFL, Trump praised car-racing league NASCAR, which saw no protests at its Sunday race in New Hampshire.
One of that league's stars, Dale Earnhardt Jr., responded on Twitter.
"All Americans R granted rights 2 peaceful protests," Earnhardt wrote. He then quoted the late President John F. Kennedy: "Those who make peaceful revolution impossible will make violent revolution inevitable."
(Additional reporting by Susan Heavey and Doina Chiacu in Washington, Gene Cherry in Raleigh, North Carolina, Dave Ingram, Angela Moon and Sheila Dang in New York, Jim Forsyth in San Antonio, and Frank Pigue in Toronto; Editing by Lisa Shumaker and Jonathan Oatis)