It was either a frightening confrontation or a misunderstanding, depending on who’s talking.

State GOP aide Matt Milner dialed 911 because he said union organizers blocked his exit and demanded he erase a video recording of Democratic Sen. Michael Bennet on Saturday afternoon following a townhall meeting sponsored by the AFL-CIO.

Mike Cerbo, executive director of Colorado AFL-CIO, said Milner came looking for trouble, but he wasn’t forced to erase the tape or barred from leaving. It’s now a matter for the Adams County Sheriff’s Office, where authorities Sunday confirmed that they received a complaint from Milner. Police also confirmed his Saturday emergency call.

“I feared for my safety. Period,” the 25-year-old Milner said Sunday.

Neither Bennet nor his staff was present at the altercation, said both Milner and a representative for the senator.

Milner has been a familiar face at about a dozen official Bennet events. The state Republican Party confirmed that it pays him to shadow and videotape the freshman senator in a practice known as “tracking.”

There was no reason to think Saturday’s gathering at the International Brotherhood of Electrical Workers’ Local 68 union hall — billed as an “everyone’s welcome” affair on the invitation — would vary from the typically uneventful routine. And for several hours it didn’t, Milner said.

But Milner, with his tripod and video camera, garnered the attention of event organizers just as Bennet bid his adieu to hundreds of audience members, some of whom had grown passionate over politically tricky labor issues, such as the Employee Free Choice Act.

The Employee Free Choice Act would make it easier for unions to organize by effectively eliminating secret-ballot elections and allowing workers to show union support by signing a form, a process known as card-check.

It’s poised to be one of the most contentious votes of Bennet’s first year, potentially affecting his 2010 campaign.

The 5-foot-6-inch Milner found himself surrounded as the event wound down, he said.

“This hulking guy comes flying at me, and he’s yelling ‘Who are you with?’ There’s a flurry of F-words,” Milner said. “They circled around me. I’d try to move, and they’d move to block my path.”

Cerbo, one of the five men who spoke to Milner after Bennet’s speech, disputed that version of events Sunday. He said the young interloper was aggressive and tried to provoke a confrontation, though he declined to say how.

“He came in uninvited. . . . I’d call him a trespasser,” Cerbo said. “He didn’t get the incident he wanted, so he’s clearly lying about what happened.”

By Cerbo’s recollection, Milner offered to erase his tape because he hadn’t been invited to the event. Milner says he was barred from leaving until he agreed to erase the recording and that one of the men briefly took his camera to make sure it was.

Jessica Fender: 303-954-1244 or jfender@denverpost.com