John Dennis sits in the back room of Perry's in Pacific Heights, reflecting aloud over a cup of tea on the personal liberties he believes House Speaker Nancy Pelosi has stripped from him. In blazer and jeans, with silver hair and pale blue eyes that match the color of his shirt, Dennis more closely resembles a relaxing yachtsman than a thrower of political brickbats.

Don't be fooled. A self-declared "Tea Party" Republican, Dennis is mounting a challenge to Pelosi in the 2010 race for the Eighth Congressional District, representing most of San Francisco. The Tea Party movement, an insurgency of the right's radical fringe, was credited with helping buoy the upstart candidacy of U.S. Senator Scott Brown, who pulled off an upset over his Democratic opponent last month in left-leaning Massachusetts.

"I'm a fan of the tea parties," says Dennis, a real-estate investor who actually participated in the very first tea party — a campaign event for Republican presidential hopeful Ron Paul — in December 2007. "I like them. I like what they're doing. I love the activism."

Originally from New Jersey, Dennis is the son of a union-card–carrying longshoreman and Democratic Party activist. In college, he discovered the tenets of classical libertarianism, and never looked back. "In 1984 — of all years — I read Ayn Rand," he says nostalgically. Today, his federal policy prescriptions more or less hew to those first principles. He wants to abolish the U.S. Department of Education and the Federal Reserve, and end America's wars in Iraq and Afghanistan.

It has been firmly established that many Tea Partiers are as crazy as shithouse rats. A Field Poll released last month showed that 71 percent of those who identify with the movement in California entertain the theory that Barack Obama is a foreign citizen with a forged birth certificate, and thus ineligible for the presidency. Dennis doesn't drink that Kool-Aid, but neither does he apologize for the wild-eyed proclamations of his teabagging brethren. "Look, I think it's so simple for the media to brand and categorize people," he says. "I think there are raving lunatics on the left, too."

As a practical matter, he acknowledges that unseating the most powerful woman in Congress will be an uphill struggle. (Before the general election, Dennis also has to best Dana Walsh, a businesswoman who ran against Pelosi in 2008, in the Republican primary.) San Francisco politicos aren't exactly holding their breath for a Republican upset.

"I was shocked by Massachusetts," San Francisco State political science professor Robert Smith says, "but I would have a heart attack if a Tea Party Republican beat Nancy Pelosi in San Francisco."