WASHINGTON -- President Donald Trump is indulging in his favourite kind of drama -- personal, aggressive, culturally volatile and entirely of his own making.

During a week in which a crucial Senate health care vote, his tax plan, the North Korean nuclear threat and Puerto Rico's post-hurricane suffering vied for attention, Trump carried his feud with the NFL over players who kneel in protest into the new week with a fresh volley of tweets.

"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!" he said in one of his Monday tweets.

But for some, Trump's argument with professional athletes had everything to do with race.

Rep. Hakeem Jeffries, D-N.Y., called Trump a "racial arsonist" and said he was using the manufactured controversy to pander to his conservative political base.

"He uses race to advance his own ends," Jeffries told CNN.

NFL spokesman Joe Lockhart defended players' rights to peacefully protest what they view as racial inequality and police mistreatment of black males.

"Everyone should know, including the president, this is what real locker room talk is," Lockhart said in an apparent reference to the "Access Hollywood" tapes in which Trump bragged about sexually assaulting women. Trump had chalked up those comments as "locker room talk."

Trump has a history of engaging in racially fraught battles, from spending years promoting the false story that Barack Obama, the nation's first black president, was not born in the United States, to his campaign promise to temporarily ban Muslims from the United States. He drew widespread condemnation last month for saying "both sides" were at fault for violence between white supremacists and their opponents during clashes in Charlottesville, Virginia.

Public opinion is mixed on whether professional athletes should be required to stand for the national anthem as Trump would like, and there is a racial split in how Americans process the issue.

More than half of Americans, or 52 per cent, said in a September 2016 Marist Poll that sports leagues should require their players to stand for the national anthem. While a majority of whites, 56 per cent, said standing should be required, most Latino adults, 55 per cent, and nearly half of African-Americans, 48 per cent, said athletes should not be made to stand.

As the criticism rolled in, Trump supporters argued that he was expressing patriotism, not targeting African-Americans.

"It's a perfect example of where the president gets it right," said Christopher Ruddy, the CEO of Newsmax and a longtime Trump friend. Ruddy said team officials and the news media are not in line with much of the country. "It's a win for him at the end of the day."

Trump tweeted about the issue anew Monday evening, rebutting a CNN report that White House chief of staff John Kelly was displeased with Trump's criticism of the NFL. Trump referred to the network as "fake news" and tweeted that Kelly "totally agrees w/ my stance on NFL players and the fact that they should not be disrespecting our FLAG or GREAT COUNTRY!"

The NFL spat overshadowed the beginning of a week in which Trump was expected to flesh out the tax overhaul plan he wants to sign into law by year's end, and perhaps help win over enough Senate Republicans to pass the newest health care bill. Both are top legislative priorities for him and his party.

White House press secretary Sarah Huckabee Sanders pushed back against the idea that Trump wasn't spending enough time on his agenda.

"It really doesn't take that long to type out 140 characters," she said. "And this president is very capable of doing more than one thing at a time and more than one thing in a day."

But instead of putting the public focus on health care or the tax plan, the president spent four days attacking NFL players who kneel during the national anthem.

During a political rally Friday in Huntsville, Alabama, Trump said, "Wouldn't you love to see one of these NFL owners when somebody disrespects our flag to say get that son of a bitch off the field right now, out, he's fired, he's fired."

On Saturday, Trump rescinded a White House invitation for Stephen Curry, a star player on the NBA champion Golden State Warriors.

The tweets kept coming throughout the weekend and into Monday, when he tweeted his praise for NASCAR, whose fans are predominantly white.

"So proud of NASCAR and its supporters and fans. They won't put up with disrespecting our Country or our Flag - they said it loud and clear!"

Trump's words Friday and Saturday sparked a massive show of defiance Sunday as more than 200 NFL players protested by choosing not to stand for the national anthem. Many coaches locked arms with the players.

Associated Press writer Tom LoBianco in Silver Spring, Maryland, contributed to this report