The Trump campaign rally at the BOK Center in Tulsa on June 20 had a lower-than-expected turnout. (Jabin Botsford/The Washington Post)

The Trump campaign on Sunday sought to blame concerns about protesters for the lower-than-expected turnout at the president’s Tulsa rally, even though the campaign itself had raised expectations about attendance by touting the number of people who had signed up for tickets online.

In the days leading up to Saturday night’s rally — Trump’s first since March — the president’s reelection campaign repeatedly touted figures suggesting that as many as 1 million people had signed up to attend. But the crowd did not fill the 19,000-seat BOK Center, with swaths of upper-level seating empty, and plans for a presidential speech in an outdoor overflow area were abruptly canceled as few attendees filled the space.

There were just under 6,200 people in the arena, the Tulsa Fire Marshal’s Office said Sunday. Trump’s campaign rallies have typically attracted more than 10,000 people, and some have drawn two or three times that many — although the president has a habit of inflating his crowd numbers.

President Trump’s highly anticipated return a campaign style event in Tulsa had his supporters, and Black Lives Matter protesters confronting each other. (Video: David Ly/The Washington Post, Photo: Amanda Voisard/The Washington Post)

In an interview on “Fox News Sunday,” campaign adviser Mercedes Schlapp argued that turnout was lower than expected because Trump supporters were afraid of protests outside the venue turning violent.

People were concerned about the demonstrations, Schlapp said, “and so, we saw that have an impact in terms of people coming to the rally.” Pressed by host Chris Wallace on the fact that the Trump campaign itself had raised expectations about high attendance numbers, Schlapp replied: “There were people and families that couldn’t bring their children because of concerns of the protesters.”

Schlapp also emphasized that the online reach of the event was “far and wide,” saying that more than 5.3 million people viewed it on the campaign’s digital media channels. The White House similarly fell back on claims about online viewership in January 2017 when faced with questions about the low crowd numbers for Trump’s inauguration.

Trump’s 2020 campaign manager, Brad Parscale, issued a statement Sunday morning pushing back against reports that some TikTok users and K-pop fans had sought to sabotage the rally by reserving tickets they didn’t plan to use.

The campaign had weeded out “tens of thousands” of bogus cellphone numbers ahead of the rally, Parscale said, but “these phony ticket requests never factor into our thinking” for possible crowd size.

“The fact is that a week’s worth of the fake news media warning people away from the rally because of COVID and protestors, coupled with recent images of American cities on fire, had a real impact on people bringing their families and children to the rally,” Parscale said. He added that the episode “makes us wonder why we bother credentialing media for events when they don’t do their full jobs as professionals.”

Reporters on site saw little evidence of attendees being blocked from going to the event. Outside the rally venue Saturday night, one group of protesters blocked one of three entrances for about 15 minutes — but by that point, most people had already entered the arena’s outer perimeter.

Trump complained to aides about the crowd just before he went on stage, and Parscale was spotted sitting alone in the back of the arena.

By the time Trump took the stage, there had been tense verbal confrontations outside but no reports of violence. Civilians carrying military-style rifles and pistols wandered amid the crowds, claiming they wanted to keep people safe, while Tulsa police and National Guard troops restrained and separated opposing sides.

Video: Trump’s Tulsa rally in less than 4 minutes

On the flight to Tulsa, Trump was unhappy with television images of the sparse crowds and vacant seats. He continued to fume aboard Air Force One on the way back to Washington and on Sunday, according to officials with knowledge of the conversations who spoke on the condition of anonymity because they were not authorized to speak publicly.

The president complained that his aides should have known about the efforts to embarrass him, and he argued that potential attendees were further scared away by his campaign’s public confirmation that six members of the advance team tested positive for the novel coronavirus, the officials said.

Parscale encouraged Trump aides and allies to push back hard against the crowd size narrative late Saturday and early Sunday. But several advisers blamed Parscale for setting up such high expectations for the rally, and some Republicans mused about the campaign manager’s future.

Said one Republican with direct knowledge of the president’s thinking: “We won’t really know how safe Brad is until we see how long this goes on for in the news cycle.”

Democrats on Sunday sharply criticized the Trump campaign’s decision to hold the rally amid the coronavirus pandemic. Some noted that the sign-up page for the rally contained a disclaimer noting that attendees “voluntarily assume all risks related to exposure to COVID-19” and agree not to hold the campaign or venue liable should they get sick.

In an interview on “Fox News Sunday,” Symone Sanders, a senior adviser to former vice president Joe Biden’s 2020 presidential campaign, said that Trump’s “debacle of a rally last night will long be remembered.”

Biden campaign spokesman Andrew Bates also skewered the president over his rally turnout.

“Donald Trump has abdicated leadership and it is no surprise that his supporters have responded by abandoning him,” Bates said in a statement.

Atlanta Mayor Keisha Lance Bottoms (D) accused the Trump campaign Sunday of showing “no concern for what it means for people to be gathering in large numbers.”

In an interview on CNN’s “State of the Union,” she called the rally an embarrassment and said she hoped the lower-than-expected turnout was a “preview for November.”

“Finally, people are recognizing that this man is a danger to our country, a danger to our democracy and that he should not be the president of the United States of America. . . . I just hope that this is a good sign that the country is moving on from him,” Bottoms said.

Some administration officials on Sunday defended the Trump campaign’s decision to hold a rally during the pandemic.

“I think what we saw, particularly in Tulsa, when you talk about the president’s rally, is a state in a Phase 3 reopening. And so activities like this are allowed,” acting secretary of homeland security Chad Wolf said during an interview on NBC News’s “Meet the Press.” Wolf added that it was “a personal choice that people are making on the face coverings and where you are within that phase.”

Oklahoma has recorded a rising number of coronavirus cases in recent weeks, with more than 10,000 cases and at least 368 deaths as of Sunday morning. There had also been a spike in cases in Tulsa, which led the local health department director to initially ask that the rally be postponed.

The Oklahoma Supreme Court denied a request that everyone attending the indoor rally wear a mask, and few at the event in the evening appeared to be wearing them.

The lackluster showing undercuts one of Trump’s favorite lines and political strengths: that he gets the biggest crowds of any politician.

Explaining why he would not accept a socially distanced Republican National Convention, Trump told North Carolina Gov. Roy Cooper (D) last month: “Since the day I came down the escalator, I’ve never had an empty seat.”

Robert Klemko and Adam Taylor contributed to this report.