(CNN) - Fox News talk show host Bill O'Reilly had a confrontation with a staffer for Barack Obama’s campaign that the aide and several eyewitnesses claim became physical.
The incident began when O’Reilly tried to get Obama’s attention after a Nashua campaign event. He allegedly began yelling at Obama’s National Trip Director Marvin Nicholson to get out of the way. O’Reilly then, according to eyewitness accounts, shoved the staffer.
Nicholson told CNN O'Reilly grabbed him by the arm and started "pushing" him. Nicholson also said that when he asked O'Reilly to stop pushing him, the talk-show host responded that he was "low class."
O’Reilly soon got Obama’s attention, and the two men spoke briefly.
"They shook hands and Mr. O'Reilly said that he thought Sen. Obama was great and that he loved him, and he'd love to have him on the show," Nicholson said. "And then the senator said that he would think about coming on the show after the primaries."
Then the Secret Service intervened to ask O’Reilly to step back behind the barricade that marked the press area.
Speaking later on Fox News, O'Reilly said he tried to "gently remove" the Obama staffer so his camera could get a shot of the Illinois senator.
"We're sorry we had to have that little confrontation," O'Reilly added, "but no one on this earth is going to block a shot on The O'Reilly Factor. It is not going to happen."
Related video: Obama aide: O'Reilly shoved me
– CNN's Chris Welch contributed to this report