Matt Gonzalez, San Francisco’s Green candidate for mayor, is trying to put an end to the forty-year grip the Democrats have held over the city’s electoral politics and become the nation’s most prominent elected Green. Gonzalez finished second in last month’s general election, qualifying him for the runoff on December 9.

Gonzalez, president of San Francisco’s Board of Supervisors and a former Democrat (he went Green three years ago), has mobilized a progressive coalition of artists and community activists in a grassroots effort to defeat the well-connected, well-funded and wealthy Democrat, Gavin Newsom.

Newsom, a liberal (by current Democratic Party standards) city supervisor who was practically handpicked by current Mayor Willie Brown, rose to prominence on his popular, compassionate conservative-like ballot initiative, “Care Not Cash,” which reduced the amount of financial support homeless San Franciscans can receive. The initiative was eventually thrown out by a judge and sent back to the Board of Supervisors.

Gonzalez, an advocate for tenant’s rights and environmental protection, and the sponsor of the recently passed initiative to raise San Francisco’s minimum wage to $8.50 an hour, has called the race an “ideological battle for the city” against an opponent who “always favors the money interests.” Though outspent by more than 13 to 1 by Newsom thus far, Gonzalez’s campaign has gained steam largely through a flurry of small-scale neighborhood “house parties” (they’ve planned for 100 in thirty days) and cultural events to raise money and mobilize volunteers. Some recent polls show Gonzalez with a slight edge, which has San Francisco’s Democratic establishment seeing red.

The Democratic Party appears desperate to stop Gonzalez and his progressive coalition, calling on prominent Democrats like Al Gore to make appearances in support of Newsom. While such high-profile Democrats as Supervisor Tom Ammiano, who finished fourth in the general election, former San Francisco Mayor Art Agnos and actor Martin Sheen have endorsed Gonzalez, defying pressure from the party establishment, more have succumbed.

The Green vs. Democrat theme is not likely to go away, and many within the Gonzalez camp are happy to play it up. But that’s not the only story. Just 3 percent of the city’s registered voters are Greens. Gonzalez is drawing support from Democrats who aren’t voting for him because he’s Green, but because he’s a better democrat. That’s a lesson the whole Democratic Party can learn from.