PLEASANT HILL -- In a stunning rebuke, the City Council on Monday broke with the tradition of elevating the vice mayor to the mayor's seat and bypassed Jack Weir, who has never held the top post.

On a 3-2 vote, Councilmen Ken Carlson, Tim Flaherty and Michael Harris rejected Councilman David Durant's nomination of Weir to serve as mayor for the next year. The three did not offer any explanation for their vote.

The council members split the same way on Carlson's motion to appoint Flaherty mayor.

Following the vote, Weir's family, including his wife, son and brother, former Contra Costa County Clerk Steve Weir, filed out of the chamber in disgust. Later, Steve Weir denounced the council's decision.

A clearly stunned Jack Weir said, "If you will excuse me, I'll be leaving the council meeting at this point. I will be at future council meetings."

"I am humiliated and I'm embarrassed for this council," he added. "I think what you did is inappropriate and an embarrassment to this city."

After Weir's departure, the council elected Carlson vice mayor by a vote of 4-0.

Although passing over the vice mayor isn't unprecedented in Pleasant Hill, it has rarely been done. In 1990, Vice Mayor Sherry Sterrett lost her bid to become mayor.

In the 2010 election, Weir faced off against incumbents Harris and Terri Williamson. Weir, who linked his campaign with the effort to defeat an unpopular proposal to raise the city's utility tax, received the most votes and pushed Williamson out of the seat she had held for 25 years. Harris and Weir are up for re-election next year.

Weir is arguably the most conservative member of the council, and his stance on the issues has led to robust -- and sometimes prickly -- debate; most recently during consideration of an ordinance to regulate firearms dealers.

Following the meeting, Carlson said his decision wasn't motivated by political differences. In fact, Carlson pointed out that he sometimes holds the same position as Weir. For example, both men voted against the firearms ordinance. Rather, Carlson said he has questions about Weir's leadership abilities.

Without revealing details of a discussion that took place in a closed session, Carlson said Weir had "backed out" of a negotiated compromise related to City Manager June Catalano's performance review.

"I think if you make an agreement, you follow through on it," said Carlson, who was elected last year.

Harris, the outgoing mayor, declined to explain why he voted against Weir saying only, "I think Tim will do an excellent job of representing the citizens of Pleasant Hill."

Flaherty, an attorney and former planning commissioner, eked out a win for the third council seat in 2012. He also chose not to say why he didn't support Weir.

"It was a very difficult vote. I respect Jack's passion and I have enjoyed being seated to his left this past year and I look forward to moving to the center of the dais," the newly selected mayor said.

While Flaherty said he hopes the council's decision was the best for the city, he acknowledged that it may strain relationships.

"I think it's going to take some time to let this settle. Clearly, Jack was upset and understandably so," Flaherty said.

Durant said he voted for Weir to uphold the council's tradition of promoting the vice mayor and because he believes Weir has served honorably and with distinction. Although Durant wasn't entirely surprised by Monday's outcome, he was disappointed.

"It just seems crass to have deprived Jack of the honor of serving as mayor," he said.

Furthermore, Durant said he believes there should be public accountability if council members decide to forgo the normal rotation.

"My worry is that deciding this way for no apparent, stated reason will signal a change for the way the city operates," he said.

Lisa P. White covers Martinez and Pleasant Hill. Contact her at 925-943-8011. Follow her at Twitter.com/lisa_p_white.