San Francisco's long-simmering labor war erupted last month with neither a bang nor a whimper but a conundrum. Attendees at the Labor Council's annual fundraising banquet were beset with a spectacularly San Franciscan paradox: The city's most stalwart labor backers heading to the year's most stalwart labor-backing event were confronted by a group of labor stalwarts picketing the premises.

What do you do when a labor group pickets a labor gathering?

The rift festering within the city's labor movement was no secret to those peeking behind closed doors. But now it's out in the open. Which is just how the members of the San Francisco Building and Construction Trades Council who upended organized labor's big night wanted it.

"Well, it's public now," says one building trades member, "and a lot of people are happy about that."

The image of trade unionists in their satin jackets excoriating one another while, perfunctorily, concluding each sentence with "brother" or "sister" is amusing enough. But the events of April 24 carry serious consequences. They could, quite realistically, mark the opening salvo of a destructive labor civil war. High-ranking ­— and rather sane ­— San Francisco union officers tell your humble narrator that the possibility of the building trades seceding from the Labor Council isn't just possible ­— but desirable.

The city's fattest fat cats know this. And they're pleased. In San Francisco, it's getting ever harder to describe the city's unions as united. And that could hurt you, even if you haven't got a satin jacket in your closet.

There's an old joke about two strangers meeting on a remote bridge. A conversation ensues and both realize they're fervent Christians. In fact, they're both Protestants. What's more, they're both Baptists. Even better, they're both Reformed Baptist Church of God.

"Are you Reformed Baptist Church of God, Reformation of 1879, or Reformed Baptist Church of God, Reformation of 1915?" the first man asks. "Reformed Baptist Church of God, Reformation of 1915!" affirms the second.

His companion shouts "Die, heretic!" and hurls him from the bridge.

San Francisco politics is like that. Those who master it may yet find their names affixed to a bridge. The mutual enmity between the city's political camps increases with their proximity on the political spectrum. This November, San Francisco voters will elect their next assemblyman: a Harvard-educated lawyer and member of the Board of Supervisors named David or a Harvard-educated lawyer and member of the Board of Supervisors named David.

This decision may be the David that breaks the city labor movement's back. The builders are backing David Chiu. The Labor Council ­— the umbrella organization for all San Francisco unions ­— is emphatically backing David Campos. The builders want their donations back. The Labor Council already cashed the checks. And now an out-and-out split is being discussed openly.

Die, heretic.

From a purely realpolitik point-of-view, the building trades' theatrics make little sense. This is, after all, a land-use issue. It always is in this city, especially with the building trades. They want things built, they want things built union, and they want things built yesterday. 'Nuff said.

The builders feel Chiu is more amenable to this than Campos; he's played ball with them more regularly and they'd like that to continue in Sacramento. And yet, an assemblyman has a hell of a lot less input on local development than a supervisor. If Campos were to matriculate to the Capitol, the builders would arguably be better off. Development-enthralled Mayor Ed Lee would appoint Campos' successor in the progressive stronghold of District 9 ­— and Chiu would still be here to vote the way the building trades prefer on projects like Park Merced or Candlestick Point.

Building and construction union higher-ups don't deny this. But they also say it "would send a bad message" to "reward" Campos with a trip to the State House. As such, members of the building trades are talking about tossing the rest of organized labor aside and lining up with their more natural allies: business and development interests.

Building things in San Francisco requires immersing oneself in a tried-and-true ritual. If you're sympathetic to the labor cause, you'd call it "negotiating" with the city, its unions, and the politicos they support. If you're not, the term "extortion" might come into play. Either way, the forces transforming this city aren't doing so out of a sense of beneficence for the common man. Developers seem to be doing decently for themselves. Their projects certainly seem to be mushrooming in a city once more inundated by cranes.

But, with a fractured labor movement, that could change.

Labor solidarity works for San Francisco workers when concessions are made in the near- and long-term. Yeah, it'll get built and built union. But the future janitors and service workers: They get union commitments, too. The hotel workers and others get "card-check neutrality" ­— a pledge to recognize a union if a majority of workers sign up for it. This process can result in benefits for even those not in unions: Parks are funded. Behested payments are made toward playgrounds or similarly feel-good city amenities.

Ideally, a functioning labor movement really ought to benefit those outside the satin-jacket set. So, if you like seeing things get built, it could work for you. If you like the notion of a high minimum wage, it could work for you. And if you're copacetic with publicly financed city health care, then it's certainly working for you.

All of this takes time. Builders don't like to wait. A crappier, less inclusive deal now is preferable to a superior arrangement months or years down the road.

With a splintered labor movement, however, the powers that be will have the opportunity to offer those crappier deals. Like medieval Catholics answering to popes in both Avignon and Rome, developers can weaken and divide city labor by picking and choosing which of its demands will be accommodated and which will be ignored. So, sure, developers may agree to "build union." But a living-wage commitment or benefits for future service workers? Forget it.

The Labor Council will have something to say about that. Decoupled from the building trades, it'll be far more emboldened to kill a project outright if it doesn't get what it wants for its remaining membership.

In short: If you think the building and development process is nasty and brutish now ­— you just wait.

San Francisco is a place that tests one's liberal credentials. And yet, even in this city, anti-union rhetoric is finding an increasingly receptive audience. That's not hard to figure: Public-sector unions are an anathema to the John Galt fan club pervading San Francisco. Union workers' solid wages, rich benefits, and guaranteed pensions are the envy of college-educated baristas with six roommates. But power doesn't exist in a vacuum. If organized labor loses ground in this city, other forces will gain ground. And those forces don't figure to be the sort offering much in the way of concern for the city's less well-off, or doling out even trickle-down benefits.

In any event, the ball is in labor's court. It all comes down to whether they opt to build bridges ­— or hurl each other off of them.