Donald Trump during a primary night event in Palm Beach, Fla., on Tuesday. At left is his campaign manager, Corey Lewandowski. (Gerald Herbert?AP)

TUCSON, Ariz. — Donald Trump’s campaign manager, Corey Lewandowski, is under heavy scrutiny after video footage surfaced Saturday showing him and an unidentified man forcefully engaging with a demonstrator at a rally here.

The video shows Lewandowski and the man reaching for a young protester in the stands amid a large group of anti-Trump demonstrators congregated in a section of the Tucson Convention Center. The footage shows the protester being pulled backward. The protester then begins to push the man to Lewandowski's left.

Speculation about whether Lewandowski or the other man were responsible for the forceful contact has circled on social media — but there has been no clear consensus.

The incident has, nonetheless, raised questions about the necessity and propriety of Lewandowski’s presence in the crowd, particularly after a Breitbart reporter accused him of manhandling her at a Trump campaign event earlier this month. Lewandowski has been regularly spotted helping to escort unruly protesters at campaign rallies across the country.

“Additional security measures will be put in place moving forward," Lewandowski said in a statement to The Washington Post when asked whether he will continue to assist security detail in handling protesters.

The Trump campaign has been under intense scrutiny in recent weeks over escalating clashes between protesters and supporters, including several instances of physical altercations. In one instance Saturday, a man assaulted a protester who was being escorted out with a friend wearing a Ku Klux Klan hood. The assailant punched the protester and proceeded to kick him repeatedly.

Trump's critics say he has encouraged violence against protesters at the rallies. His supporters say the protesters are intentionally stirring trouble.

Trump expressed support for Lewandowski on Sunday morning when asked about the incident on ABC's "This Week."

“I will give him credit, spirited,” Trump said about Lewandowski being in the crowd. “I give him credit for having spirit. He wanted them to take down those horrible profanity-laced signs.”

“Security at the arena, the police were a little bit lax. And…they had signs up in that area that were horrendous, that I cannot say what they said on the sign. But the ultimate word, and it was all over the camera,” Trump said. “Frankly, the television cameras can't take it and they can't do anything about it."

The campaign said Saturday that Lewandowski was not responsible for yanking the young man. Here's the statement in full:

 Corey Lewandowski was speaking with a protestor at today’s rally in Tucson, Arizona, when the individual he was speaking with was pulled from behind by the man to Lewandowski’s left. The video clearly shows the protestor reacting to the man who pulled him, not to Mr. Lewandowski. The man to Corey's left who pulls the protestor back and many other people in the scene are reacting to the protestor grabbing the woman in the green shirt. Mr. Trump does not condone violence at his rallies, which are private events paid for by the campaign.