The topic was whether to resume playing college football amid the coronavirus pandemic. The Fox Sports Radio program was in full swing. And President Trump called in live on the air Tuesday, offering some opinions.

Colleges are “making a tragic mistake” if they cancel their seasons, he told host Clay Travis, who gained prominence three years ago for citing his allegiance to “the First Amendment and boobs” on CNN.

After all, Trump continued, the players are “so powerful and so strong and not lots of body fat . . . maybe none, in some cases” — so they are at less risk of getting sick. “It just attacks old people,” he declared, though a study released this week found 97,000 children in the country tested positive for the virus in the last two weeks of July, a 40 percent increase.

However, on professional football, the president had some reservations. The National Football League, Trump said, “wants to open very badly” and is working with his administration to do so safely. But, he added, referring to his ongoing spat with NFL players who began kneeling in 2017 to protest police brutality, “if they don’t stand for the national anthem, I hope they don’t open.”

As the nation debates the efficacy of whether it is safe and worthwhile for big-revenue sports leagues to resume playing, the First Fan has again inserted himself into the cultural mix from the sidelines — taking potshots on Twitter and delivering hot takes with the enthusiasm reminiscent of overheated sports talk radio — “Donny from Queens,” as the Bulwark opinion journal joked in a headline.

Yet in the face of a deadly pandemic that has killed more than 160,000 Americans on his watch, Trump’s musings have potentially deadly consequences as league commissioners and university chancellors weigh the complicated mix of public health, revenue considerations, fan sentiment and political pressure. Hours after Tuesday’s show, the Big Ten became the first major college football conference to cancel the fall season, with hopes of playing the in spring instead. The Pac-12 later followed suit.

On Travis’s show, Trump seemed to reveal that his push to restart the college games is not based foremost on scientific evidence about the dangers of spreading the illness — but rather on his political incentives.

Trump has tied himself closely to college football, whose fan base skews conservative in the South and Midwest. On the show, he praised coaches Nick Saban of the University of Alabama and Ed Orgeron of Louisiana State University, as well as former Notre Dame coach Lou Holtz, whom he called “a friend of mine” and “a supporter from the beginning.” Orgeron returned the praise, telling reporters that Trump’s remarks “make me proud” and saying the president is “doing a fantastic job.”

But Trump has feuded with the NFL since 2017 when some players began kneeling, an act Trump has cast as disrespecting the American flag and the military.

“Frankly, if the NFL didn’t open, I’d be very happy — if they don’t stand for the flag and stand strongly,” Trump told Travis.

The National Basketball Association has drawn widespread praise for taking the extreme step of creating a confined bubble for all of its teams in Orlando and testing heavily since resuming a season interrupted in March. The NBA was the first major professional league to shut down, after Rudy Gobert of the Utah Jazz tested positive for the virus.

But on the radio program Tuesday, Trump made no mention of those safeguards, instead choosing to belittle the NBA for its embrace of the Black Lives Matter movement. Players have worn jerseys with slogans supporting the cause.

“Look at the basketball ratings. They’re down to very low numbers — very, very low,” Trump said, adding that “people are angry about” the activism. Viewership of televised games slipped 4 percent in the first week after the restart compared with the pre-hiatus games, though prime-time ratings are up 11 percent, according to media reports.

Later in the show, Trump acknowledged his personal beef with the players, calling them “very, very nasty and, frankly, very dumb,” after Travis asked about their criticism of him. In 2017, Trump rescinded an invitation to the NBA champion Golden State Warriors for a traditional White House visit after star guard Steph Curry, who has golfed with former president Barack Obama, said he had no interest in meeting Trump.

That Trump would eschew a chance to tout the success of the NBA in restarting relatively safely is predictable, given his proclivity to take almost everything personally, but also curious given his eagerness to boost the economy and juice his sagging public approval ratings.

Epidemiologists cautioned that the president was not just disseminating misinformation but also failing to enunciate ways his administration could help sports leagues create safe conditions to restart the games. Despite Trump’s suggestions otherwise, young, otherwise healthy athletes maintain risks of significant complications and perhaps permanent injuries from the coronavirus, doctors say.

“There does not seem to be a focus on what needs to be done to make it safe rather than just asserting, ‘This outcome should occur,’ ” said Steven Goodman, an epidemiology professor at Stanford University. “If he would spend equal time talking about the national plan to keep the same groups safe, there might be some credibility to these claims. In absence of that, it looks like these statements put players and coaches in harm’s way if they play without adequate safety measures.”

Trump, a former television reality-show star, had clearly spent time thinking about the optics of the games, which are being played without live audiences.

The Professional Golfers’ Association, Trump opined, “looks more beautiful, if you want to know the truth,” and the Ultimate Fighting Championship “works very well.” Trump, an avid golfer, has played with professionals Tiger Woods, Rory McIlroy and Dustin Johnson, and he attended a UFC bout last fall with that organization’s president, Dana White.

“They light up the cage and it’s really bright . . . maybe put a little silk around it,” Trump marveled of the UFC, before reiterating that “basketball is not working because of the way they treated our flag and our anthem.”

By comparison, Trump said the National Hockey League is “doing very well,” suggesting one reason is because the players have not embraced the social justice movement — even though four players took a knee last week during the U.S. and Canadian national anthems. The NHL has temporarily relocated all of its teams to Canada — where coronavirus rates are far lower than in the United States — but Trump made no mention of that.

He also said he hasn’t watched enough of Major League Baseball to render a judgment. That league has been forced to cancel games since restarting last month, after several teams registered outbreaks of the virus.

“The virus has the last word,” said Goodman, the epidemiologist. “If a team starts playing and all sudden they don’t have an offensive line and they don’t have a backup line, they can’t play — independent of what the president or coaches or college presidents are saying.”

If colleges resume playing, he added, “the season will be three-fourths over well before Election Day. We will know what the virus has said.”