The popular, labor-backed mayor of Duluth faces a lifetime ban from the local union hall after he ate lunch at a local restaurant and, according to the union, crossed a picket line to get there.

Mayor Don Ness, a Democrat who was so popular after his first term in office that he ran unopposed for a second term in 2011, told supporters on Facebook that he has another side to the picket line story, but so far the first-of-its-kind ban remains in place.

Numerous union officials contacted for the story said they had no comment.

The Painters and Allied Trades Local 106 ran the picket line at the Radisson Hotel Duluth because members believe the hotel hired nonunion workers to renovate some of its hotel rooms, according to Dan O’Neill, president of the Duluth AFL-CIO Central Labor Body. He said Ness approached the picket line, shared a few words with the picketers and then went into the building.

“We were really surprised that the mayor went in,” said O’Neill. On Sept. 10, union members attending a Duluth Central Labor Body meeting voted to ban Ness from the Labor Temple’s Wellstone Hall at 2002 London Road. Ness said he learned about the ban from the union newspaper.

Ness, whose wife worked for Wellstone’s Duluth office, told his supporters on Facebook that he’s confused and upset by the ban. “This is still an incredibly hurtful situation,” he wrote on Facebook, adding that it will tarnish his final months in office. Ness announced last year that he doesn’t plan to run for a third term.

First elected at age 33, Ness has long been known as a mayor with a penchant for social media, and he has a broad online following.

Venting on Facebook, Ness characterized the ban as a petty maneuver based on a misunderstanding.

He wrote that he had been invited to lunch at JJ Astor, the restaurant on the 16th floor of the Radisson, and spoke to the picketers outside the hotel on his way in.

“Then I went to lunch at a union restaurant staffed by union employees,” he wrote. Ness said unionized restaurant employees crossed the same picket line, and that it was his understanding that others were allowed to cross without problems.

“If this was a strike, I absolutely would NOT have crossed the line,” he added.

Ness went on to write that he’s had arguments with labor leaders from time to time during his tenure as mayor, but that he’s agreed with them 90 percent of the time, and has a long list of labor credentials.

His Facebook post on the ban has been liked more than 5,000 times, something O’Neill said labor leaders were aware of.

“That’s a lot of likes,” said O’Neill. At least one union remains in support of Ness: the Carpenters Local 361 union posted on Facebook that “Mayor Don Ness is welcome in the Carpenters Local 361 building any time. The actions of a few radicals in the Central Labor Body does not fairly represent all of Duluth’s Labor.”

On Thursday evening, O’Neill and Ness both told the Star Tribune that they thought the ban might be rescinded or that some kind of meeting between Ness and the union might happen to resolve the ban.

Ness, who has been at a mayoral conference in Seattle this week and had plans to spend time with Duluth musician Charlie Parr, who was touring the area, could not be reached for comment Friday. O’Neill said Friday he had no comment.