NASHUA, N.H.-- Fox News host Bill O'Reilly got into a confrontation with an Obama aide after O'Reilly started screaming at him as he tried to get Barack Obama's attention following a rally here. O'Reilly eventually did chat briefly with Obama and asked him to be a guest on his show.

The incident was triggered when O'Reilly - with a Fox News crew shooting - was screaming at Obama National Trip Director Marvin Nicholson "Move" so he could get Obama's attention, according to several eyewitnesses. "O'Reilly was yelling at him, yelling at his face," a photographer shooting the scene said.

O'Reilly grabbed Nicholson's arm and shoved him, another eyewitness said. Nicholson, who is 6'8, said O'Reilly called him "low class."

"He grabbed me with both his hands here," Nicholson said, gesturing to his left arm and O'Reilly "started shoving me." Nicholson said, " He was pretty upset. He was yelling at me."

Secret Service agents who were nearby flanked O 'Reilly after he pushed Nicholson. They told O'Reilly he needed to calm down and get behind the fence-like barricade that contained the press.

Obama had his back turned at this point and did not see any of this.

O'Reilly yelled "sir" at Obama and Obama walked over, not aware of what happened and told him he had an overflow crowd to visit. According to the time code from a photographer shooting the two, Obama and O'Reilly talked near 11:45 a.m. eastern time.

He just came right around the barricade. They shook hands and Mr. O'Reilly said he thought Sen. Obama was great and that he loved him and loved to have him on the show and said he would think about coming on after the primaries.

The situation took place near risers in the gym at Nashua North High School where Obama just addressed a jammed rally.