DENVER — Flanked by a throng of city cops, more than a dozen Green Party activists loudly disrupted the only live televised U.S. Senate debate between Michael Bennet and Darryl Glenn, pounding on the glass walls of a downtown state museum and chanting “open the debate” so loudly the moderators had to address it.

Inside the Anschutz Hamilton Hall on the first floor of the History Colorado Center, incumbent Democrat Bennet and Republican Glenn faced off in their second— and final— head-to-head debate in the U.S. Senate race.

Outside, led by Green Party U.S. Senate nominee Arn Menconi and a man in a white bunny suit, the activists pounded on the museum’s large glass doors and walls, and chanted so loudly it became hard for audience members to hear the two candidates speaking from their podiums inside.

About 10 minutes in, the demonstration forced the debate’s moderators, 9News anchor Kyle Clark and political reporter Brandon Rittiman, to acknowledge it live on the air. Following a portion of the debate about Glenn’s opposition to President Barack Obama’s Trans-Pacific Partnership global trade agreement, Clark paused to face the camera.

“What folks are hearing at home that sounds like a very spirited drum circle are protesters who are beating on the outside of the building,” he said. “We assume that they’re probably in support of one of the half-dozen minor party or unaffiliated or write-in candidates who are also in this race but are not on the debate stage tonight.”

Clark said 9News, Denver’s local NBC affiliate, uses a 10 percent threshold from two polls of the station’s choosing to decide who gets to participate in their debates.

“Some folks are exercising free speech outside by using the building as a bass drum,” Clark said.

At one point, the chanting and glass-pounding grew so loud that Glenn asked a moderator to repeat a question. Frustrated, museum security asked local police to intervene.

But there was a twist: The museum is state property, which officers interpreted as being outside the jurisdiction of the city’s cops.

As protesters slammed on the glass and waved signs like “Your silence to our voices speaks volumes,” Denver Police Sergeant J. Lucero said officers were trying to figure out whether they could make arrests or would need to call in state authorities.

At one point, Lucero pulled Menconi aside to explain the situation, saying he was a firm believer in the First Amendment and showing Menconi which part of the surrounding area was state owned and city owned.

Menconi, an energetic social justice advocate and former Eagle County Commissioner with a greying beard who is running a campaign against the TPP, war and fracking, and is pushing for universal healthcare and curbing global warming, rallied his supporters to a chant of “Black Lives Matter,” a reference to Glenn’s oft-stated position that “All lives matter.”

John Vegil, 54, a local cannabis worker, veteran and a registered Democrat, said he heard about the demonstration on social media and decided to join.

“The fact that our democracy has been hijacked by the corporate elite, that’s why I’m here,” he said. “I’m not down for that.”

Green Party member Susan Hall, a teacher, said she took part in the protest in hopes that it might change the mind of a voter who noticed.

“It’s not right to shut out people,” she said.

There are about 13,000 registered Green Party members in Colorado. For comparison, there are about 40,000 registered Libertarians.

Other non-major party names on this year’s U.S. Senate ballot include Libertarian Lily Tang Williams, Unity Party candidate Bill Hammons and unaffiliated candidates Paul Fiorino and Dan Chapin. Write-in candidate Don Willoughby is also running.

You can watch a recent debate in Pueblo among Menconi, Fiorino, Chapin and Willoughby here.

Outside the museum, the man in the bunny costume, who did not give his name, said in his experience passersby will stop and read a sign if it is carried by a rabbit.

Said the bunny: “I’ve had [the suit] for years just for such occasions.”