Green Party Senate candidate Aaron Dixon was arrested Tuesday after he refused to leave the KING-TV building where three other candidates...

Green Party Senate candidate Aaron Dixon was arrested Tuesday after he refused to leave the KING-TV building where three other candidates were taping a debate.

A KING-TV video showed Dixon being led out of the lobby by police officers and then handcuffed as his supporters chanted, “Let him go!”

Dixon entered the building in an attempt to join the debate, which he had been excluded from, said his campaign manager, Jesse Hagopian. Dixon was arrested, taken to the Seattle Police Department’s West Precinct and then released.

Police wouldn’t identify the man arrested for investigation of criminal trespass because he hadn’t been formally charged. Police spokeswoman Debra Brown said the person was asked to leave the KING-TV lobby but refused.

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Republican Mike McGavick, Democratic Sen. Maria Cantwell and Libertarian Bruce Guthrie were at the station to tape a debate that aired Tuesday night.

Dixon wasn’t invited to participate because he couldn’t show the minimum public support or fundraising required by KING-TV. The criteria were based on guidelines established by the Debate Advisory Standards Project, a nationally recognized group.

The debate was co-sponsored by The Seattle Times.

After the arrest, about 35 Dixon supporters marched several blocks from the television station to the West Precinct. They then marched back to the TV station, where they rejoined a crowd of political activists.

Hagopian said the campaign had launched an effort earlier to get Dixon included in the debate.

“You really can’t claim to be a democracy when you silence the only black voice in the debate, you silence the only progressive anti-war voice in the debate,” Hagopian said.

More than 40 supporters of Cantwell and McGavick camped outside the KING-TV building during the debate, waving signs and yelling campaign slogans.

Dixon, 57, runs Central House, a Seattle nonprofit that provides transitional housing for homeless young adults and leadership training in local high schools. He was a civil-rights activist in the 1960s who organized sit-ins, and was the leader of the local Black Panther Party.

Guthrie qualified for the debate after he loaned his campaign $1.1 million of his own money. Cantwell and McGavick have raised millions in campaign contributions.

Ray Heacox, president and general manager of KING-TV, said in a written statement that the “issue of when to include a third-party candidate in a debate is one of the most difficult issues in covering politics.”

“Our goal is to have a public discourse on the issues,” Heacox said. “We invited all the Senate candidates to participate in the debate under the condition that they met any one of a number of criteria to establish their viability.

“It is unfortunate that Mr. Dixon did not meet any of those criteria. It is also unfortunate that he refused to leave the premises when asked to do so,” Heacox said.

The Associated Press contributed to this report.

Jennifer Sullivan: 206-464-8294 or