A week after the Nov. 13 Paris attacks, Republican presidential candidates are still discussing American Muslims and their stances on Syrian and Iraqi refugees. (The Washington Post)

Donald Trump on Sunday defended erroneous claims he made about U.S. Muslims cheering the 9/11 attacks and said a black protester at a weekend rally here was “so obnoxious and loud” that “maybe he should have been roughed up” by white audience members.

The Birmingham rally marks the latest example of Trump’s refusal to back down amid outcries over his often-incendiary racial and religious rhetoric — and comes as polls show him once again with a clear lead over the rest of the candidates seeking the Republican Party’s presidential nomination.

Saturday’s racially charged altercation occurred in Birmingham, famous in the 1960s as a center of the civil rights struggle. The thousands who attended Trump’s rally were nearly all white in a city with a black majority.

Mercutio Southall Jr. — a well-known local activist who has been repeatedly arrested while protesting what he says is unfair treatment of blacks — interrupted Trump’s rally and could be heard shouting, “Black lives matter!” A fight broke out, prompting Trump to briefly halt his remarks and demand the removal of Southall.

“Get him the hell out of here, will you, please?” Trump said Saturday morning. “Get him out of here. Throw him out!”

At a campaign event in Birmingham, Ala., on Saturday, Nov. 21, Republican presidential candidate Donald Trump demands the removal of a well-known activist Mercutio Southall Jr. after he shouts, "Black lives matter!" (Reuters)

At one point, Southall fell to the ground and was surrounded by several white men who appeared to be kicking and punching him, according to video captured by CNN. A Washington Post reporter in the crowd witnessed one of the men put his hands on Southall’s neck and heard a female onlooker repeatedly shout, “Don’t choke him!”

As security officers got Southall on his feet and led him out of the building, he was repeatedly pushed and shoved by people in the crowd. The crowd alternated between booing and cheering. There were chants of, “All lives matter!”

“Maybe he should have been roughed up, because it was absolutely disgusting what he was doing,” Trump said on the Fox News Channel on Sunday morning. “I have a lot of fans, and they were not happy about it. And this was a very obnoxious guy who was a troublemaker who was looking to make trouble.”

That was a change in tone from just a month ago, when Trump would regularly tell his audiences not to harm the protesters who often infiltrate his rallies.

“Don’t hurt ’em,” Trump said at a rally in Miami on Oct. 23 as pro-immigration activists were led out. “You can get ’em out, but don’t hurt ’em.”

Also at the Birmingham rally, Trump claimed he watched as “thousands and thousands of people” in Jersey City, N.J., cheered the fall of the World Trade Center on Sept. 11, 2001, giving the impression that he was talking about Muslims living in the United States being happy that so many Americans died in the attacks. Officials have repeatedly debunked these persistent Internet rumors — most commonly attached to Paterson, N.J., rather than Jersey City — and there is no news coverage or other evidence corroborating them.

But Trump stood by his comments during an interview on ABC’s “This Week” on Sunday, saying that the cheers came from the “large Arab populations” in New Jersey.

“It did happen. I saw it,” Trump said. “It was on television. I saw it.”

But Jersey City Mayor Steven Fulop said on Twitter that Trump “has memory issues or willfully distorts the truth, either of which should be concerning for the Republican Party.” In a statement, the Anti-Defamation League called Trump’s claims “irresponsible” and “factually challenged.”

Jerry Speziale, the Paterson police commissioner, told The Post’s Fact Checker: “That is totally false. That is patently false. That never happened. There were no flags burning, no one was ­dancing.”

Trump, who led the field at 32 percent in a Washington Post-ABC News poll released Sunday, has long made provocative statements a hallmark of his campaign. Critics and rivals have said that Trump is stoking racial tension. Former Florida governor Jeb Bush said Trump’s comments about Islam are “manipulating people’s angst and their fears.”

After the Birmingham altercation, Southall told the AL.com news site that the commotion started as he began recording himself and other protesters at the rally and saying that he wanted “Donald Trump to know he’s not welcome here.” Southall said someone knocked the phone out of his hand and made a racial slur. Then there was pushing, Southall told the news site, and punches started flying.

A swarm of security officers quickly made its way through the crowd of several thousand, got Southall off the ground and walked him out of the building. Trump has had Secret Service protection since Nov. 11, and those who attend his rallies and political events must now walk through metal detectors and have their bags searched.

As Southall was removed Saturday, Trump recounted how Bernie Sanders, candidate for the Democratic presidential nomination, responded to “Black Lives Matter” activists who came onstage during an event earlier this year.

“You see, he was politically correct,” Trump said. “Two young women came up to the podium. They took over his microphone. I promise you, that’s not going to happen with me. I promise you. Never going to happen. Not going to happen. Can’t let that stuff happen.”

Before the fight broke out, Trump had warned the audience that Islamic State fighters might recruit their children online and called for an impenetrable wall along the southern border, prompting the crowd to chant: “Build a wall! Build a wall! Build a wall!” In his nearly hour-long speech, Trump listed graphic details of killings committed by people who had entered the country illegally, promised to bar Syrian refugees from living in the United States because they might be terrorists and called for heavy surveillance of “certain mosques.”

From the media area, reporters strained to see what was happening. CNN reporter Jeremy Diamond managed to make a video of the incident before Trump staffers forced him back into the media pen. As the video circulated on social media that night, some of Trump’s supporters took to Twitter to call the protesters “thugs,” “Dem plants” and a variety of obscene names. Several wrote that the protesters opened themselves up to the possibility of violence by attending the rally.

Trump grew agitated as reporters shifted their focus to the protesters.

“Look at those bloodsuckers back there,” Trump said. “They’re turned around, and they’re following the people, right? Because you have a small group of people that made some noise and are being thrown out on their ass. Right?”

The crowd roared with cheers.

Amber Phillips and Glenn Kessler in Washington contributed to this report.