San Francisco ? Gavin Newsom, 36, a fourth-generation San Franciscan who has just become this city’s youngest mayor in a century, is, of course, a Democrat. He also is tall, dark and handsome, a self-made millionaire from restaurant and wine businesses, whose wife is described as a prosecutor, television legal analyst and “former lingerie model.” Newsom barely won, even though he was endorsed by Democratic luminaries Bill Clinton, Al Gore and most of the presidential aspirants. But not by Howard Dean, which may say something about the limits of impulsive liberalism.

Newsom and his opponent, Matt Gonzalez, were on the 11-member Board of Supervisors, only two of whom supported Newsom. Gonzalez, the Green Party candidate, ran an Internet-driven campaign and spent one-tenth as much as Newsom but got 47 percent of the vote. Gonzalez received 10,000 more votes than Newsom on election day, but lost when the absentee ballots were counted. San Franciscans had endured three elections in 62 days — the gubernatorial recall (the city voted 80 percent against recalling Gray Davis), the first mayoral election, then the Newsom-Gonzalez runoff — which may have dampened the enthusiasm of all but political enthusiasts, who in this city are to the left of the salad fork.

Gonzalez, who once played in a punk rock band, portrayed Newsom as a protegee of outgoing — in several senses — Mayor Willie Brown, which is true. And as a child of privilege, which is nonsense. Newsom was raised by a single mother who worked two jobs. Although Gonzalez wants it known that he sleeps on a futon in an apartment he shares with three other ascetics, he refused to release his tax returns.

This city has, well, distinctive demographics. Reversing the national average, there are twice as many renters (65 percent) as homeowners. Renters, responding to the severe housing shortage that is predictably exacerbated by rent control, predictably demand more controls. They say rent control is a “diversity” measure, preventing the city from being swamped by people willing to pay the market price of housing.

Seventy percent of adults here are single. The city evidently has more dogs than children, and Newsom says the endorsement of a dog — well, dog owners — political action committee is much coveted. But strike the word “owners.” Gonzalez authored the ordinance stipulating that pets will also have “guardians.” Can you be arrested for saying just “owner”? Newsom languidly says, “You don’t get arrested for much else out here.”

The city has about as many camels as Republicans, so Newsom is called a “conservative.” This smear gained currency even though Newsom supports “transgender rights,” meaning the city pays for its employees’ sex change operations, including — this may be more than you want to know — expensive hormone treatments. Newsom courted the large LGBTQI constituency, an acronym he can almost explain. It stands for lesbians, gays, bisexuals, transgender people, questioners and “intersex.” What is that last group? He is not sure.

Newsom does say inflammatory (to “progressives”) things like: “You can’t redistribute wealth you don’t have.” And he does not share progressives’ enthusiasm for shuffling students around to fine-tune each school’s “diversity index.” There are fewer than 60,000 public school pupils left, half of whom speak a language other than English at home. Newsom says the high school dropout rate is high, and the average Latino grade is only slightly higher than the black average of D or D-plus.

San Francisco spends more than any other city on the homeless, so naturally it has more homeless people per capita than any other city. Newsom authored the “Care not Cash” bill to provide treatment and housing rather than cash, which attracts the homeless, who use cash injudiciously. Voters loved Newsom’s idea, but progressives like Gonzalez and their allies in the judiciary have blocked it.

Newsom says “no one knows” how many homeless there are, partly because progressives have blocked the gathering of data. He guesses there are between 5,000 and 15,000, with a chronic street population of 3,500. Arrest someone for aggressive panhandling and, Newsom says, a pro bono attorney appears to fight a $50 fine that cannot be collected anyway.

Gonzalez did what Dean has done: he told the left that its hour had come around at last. The Iowa result suggests that Democrats understand the warning that radiates from San Francisco, America’s most hospitable habitat for Deanism.

That impulse, or something very like it, crested short of victory. If it can’t make it here, it can’t make it anywhere.

George Will is a columnist for Washington Post Writers Group.