WASHINGTON (Reuters) - NFL team owners will consider requiring football players to stand for the U.S. national anthem after President Donald Trump on Tuesday suggested using tax laws to penalize the league for players who kneel in protest of racial injustice.

Trump, a Republican, escalated his feud with the National Football League in a Twitter post asking if the league should get tax breaks while some athletes kneel in protest when the “Star-Spangled Banner” is played at the start of each game.

“Why is the NFL getting massive tax breaks while at the same time disrespecting our Anthem, Flag and Country? Change tax law!” Trump wrote on Twitter.

The world’s top-grossing sports league gave up its tax-free status two years ago. Its owners are preparing to address the anthem issue at their fall meeting in New York Oct. 17-18, NFL chief spokesman Joe Lockhart told reporters on a conference call on Tuesday.

“Everyone at this point is frustrated by the situation,” Lockhart said. “The commissioner and the owners do want the players to stand. We think it is an important part of the game.”

The protests, in a league where African-Americans make up the majority of players, have continued through the season, with some players taking a knee when the anthem is played and others standing arm-in-arm in solidarity.

Current policy calls for players to stand for the anthem and face the flag, but no player has been disciplined for a protest, Lockhart said.

“We need to move past this controversy, and we want to do that together with our players,” NFL Commissioner Roger Goodell wrote in a memo to team owners.

The White House supported the idea of asking players to stand, said spokeswoman Sarah Sanders.

“We are glad to see the NFL taking positive steps in that direction,” she said at a news briefing.

Asked to explain Trump’s comment on the NFL and taxes, Sanders said, “The federal tax law doesn’t apply here, but certainly we know that they receive tax subsidies on a variety of different levels.”

The NFL Players Association, when asked for a reaction to possible changes to anthem rules, said in an email “we do not have a response at this time.”

Trump last month called on NFL team owners to fire players who kneel during the anthem to protest police violence against black Americans.

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Critics contend Trump is fanning the controversy to distract from issues including devastation in Puerto Rico after Hurricane Maria, tensions with North Korea and difficulties in pushing healthcare and tax overhauls through the U.S. Congress.

Cowboys owner Jerry Jones, speaking on KRLD-FM in Dallas on Tuesday, reiterated his stance that if any of his players chose to demonstrate during the anthem, they would not play.

“If you do not honor and stand for the flag in the way that a lot of our fans feel that you should ... if that’s not the case, then you won’t play,” said Jones.

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“That’s nothing new as far as that being my wish or the way I want the Cowboys. As far as whether or not I will basically institute or do what I said I would just say. ... I would ask anybody to look at my record relative to what I say I’m going to do.”

Vice President Mike Pence walked out of a NFL game on Sunday after some players knelt, an action some critics called a publicity stunt.

Trump won the presidency with less support from black voters than any other president in at least four decades.

Trump has squared off against the NFL before, having owned a team in the upstart United States Football League in the 1980s. That league folded in 1985 after an antitrust lawsuit against the NFL failed.

Trump has refused to disclose his own tax history, departing from a practice of U.S. presidents going back more than 40 years. Trump has said nobody cares about his tax returns, but critics say they could show conflicts of interest.