When Chicago public school teachers started the fall semester by turning down a $400 million contract offer that would have boosted pay by 16 percent over four years, my first concern wasn't for the children. It was for the Democrats.

Sure, the walkout by Chicago Teachers Union members caused havoc for kids. But I've been to public school, and I can tell you they didn't miss much.

The strike's lasting damage was to the party that since at least the early 20th century has been labor's best friend. Chicago Mayor Rahm Emanuel is not just some schmuck in the donkey party: He is President Barack Obama's former chief of staff, the congressional leader behind the Democrats' 2006 House takeover, a Clinton administration arm twister so feared that he is still known by his '90s nickname, Rahmbo.

But the strike made Chicago's tough-guy mayor look like Chuck "Bayonne Bleeder" Wepner. Striking teachers dubbed him "Empermanuel," accused him of having "no respect for us as people," and even claimed (falsely, it turned out) that Emanuel was a fan of the Canadian alt-rock quartet Nickelback. When the teachers returned to work after more than a week on the picket line, they had scored a big pay increase and crippled the teacher-evaluation testing at the heart of the strike, a resolution Emanuel unconvincingly called an "honest compromise."

Emanuel is one of many recent Democratic chief executives who have, with varying levels of enthusiasm and success, tried to confront government employee unions. California Gov. Jerry Brown struggled for two years to get a minor pension bill through the legislature. New York Gov. Andrew Cuomo in March got a partial pension reform that is expected to save $3 billion a year out of the Empire State's $133 billion annual budget. Washington, D.C., Mayor Adrian Fenty lost his job when he took on the teachers union.

And since 2006 a very similar story—of a powerful Democratic mayor being slowly pecked to death by his former union allies—has been playing out in Los Angeles. Like Emanuel, Mayor Antonio Villaraigosa looks like a throwback to the days when a union-friendly Democratic boss on Election Day could confidently send out goons to patrol the wards with two-by-fours and $50 bills.

But where Emanuel seems generally to enjoy doing public battle, Villaraigosa—palpably needy in person and heroically unfaithful to now-ex-wife Corina Raigosa (the former Tony Villar's last name is a his-and-hers portmanteau)—always seemed to be enacting an inner psychodrama on L.A.'s grand stage. The city's school district is a notorious underperformer, and to his credit Villaraigosa spent much of his first term trying to do something about it. His efforts included trying to manage a tranche of schools directly without union work rules, encouraging charter schools, and finally denouncing the teachers union in a powerful 2010 speech that earned him praise from reformers all over the country.

Unfortunately, it's not clear whether Villaraigosa, who graduated from the unaccredited People's College of Law and began his career as an organizer for United Teachers Los Angeles, wants to confront the unions or blame them for his failures. In 2007 he struck out in an attempt to win education reform in Sacramento but seemed eager to celebrate his own defeat soon after. The unions "had that place locked down," Villaraigosa told New Yorker reporter Connie Bruck. "I couldn't get a resolution that said, 'His name is Antonio Villaraigosa.' I mean, they had it locked down!" Bruck described Villaraigosa's "evident admiration for the union's display of raw power."

That don't-look-at-me attitude still informs Villaraigosa's governance. After years of dire and deteriorating finances (L.A.'s budget hasn't been balanced for four years), the mayor allows government employee unions to carry out their tactic of ensuring that any slowdown in the rate of spending increases is immediately visible to Angelenos in the form of cuts to services. Villaraigosa, whose city manager calls for taxes on real estate sales, entertainment, petroleum extraction, and parking lot revenues, seems to believe voters will respond to office-hour reductions and crossing guard–free intersections by demanding tax hikes.

To the extent possible in L.A.'s Putinesque democracy, voters actually respond by blaming the mayor. In his 2009 re-election race, Villaraigosa squeaked by with a small majority even though he was running virtually unopposed and outspent his nearest competitor (politically unaffiliated gadfly Walter Moore) by 15 to 1.

That such an unimpressive figure was chosen to chair this year's Democratic National Convention is a sign of just how shallow the Democrats' bench is. Having already been promoted several notches above his level of incompetence, Villaraigosa fulfilled party watchers' worst fears during a controversial floor vote over the last-minute inclusion of the words God and Jerusalem in the party's platform. When the voice vote split with no clear winner, Villaraigosa appeared torn between his instinct for party machine strong-arming and his longing to appear statesmanlike. Painful moments of dead air ensued, during which the nearly 60-year-old mayor looked like a little boy overwhelmed by the complexities of a man's job. At last, he unbelievably declared a supermajority, to a chorus of boos that ended up being the convention's defining moment.

There were more troubling fissures evident at the convention. Although speakers from former Michigan Gov. Jennifer Granholm to the president himself engaged in bizarre encomiums to organized labor, union members complained loudly and repeatedly to the media of feeling slighted by the party leadership. If these had been Bill Clinton's New Democrats of the 1990s, the feeling might have made sense. But the current generation of prominent Democrats is among the most union-oriented in history. They're just out of money, and the unions know it.

Rather than offering concessions to Emanuel, Villaraigosa, and other cash-strapped executives, unions have decided to go down swinging. They may be right to see compromise as death. But make no mistake: Laborgeddon is upon us, and it will have long-term consequences for the Democrats no matter who wins this election.