Peace activist Cindy Sheehan wants to snatch House Speaker Nancy Pelosi's congressional seat from her in November, but first she's going to need the help - and signatures - of 10,198 friends and supporters.

Sheehan was at San Francisco City Hall on Friday to take out papers for her independent run for Congress, but without those signatures from voters in the district, her name won't show up on the ballot.

"It's an uphill battle," said Sheehan, who vowed to run against Pelosi in July after the speaker refused to start impeachment proceedings against President George Bush. "But I'm excited about the signature-gathering process. It's going to be an opportunity to talk to people about our campaign."

The 50-year-old Sheehan, whose son, Casey, was killed while serving in Iraq in 2004, became the public face of the anti-war movement when she mounted a demonstration outside Bush's Texas ranch that lasted from 2005 to 2007.

Even after pleading exhaustion and closing down "Camp Casey" in May, Sheehan was a regular speaker at anti-war gatherings across the nation. Since moving from Dixon to San Francisco's Mission District, she's been campaigning virtually full time.

To get the signatures, equal to 3 percent of the district voters registered for the 2006 general election, the campaign will have people setting up ironing boards and card tables on street corners throughout the city, seeking voters who want an alternative to Pelosi. Sheehan has until Aug. 8 to collect the needed signatures.

Getting on the ballot will be the easy part for Sheehan. If she becomes a recognized candidate, she'll be challenging one of the best-known and most powerful Democrats in the country in Pelosi, a 10-term incumbent who routinely collects around 80 percent of the vote in the San Francisco-only district.

Election challenges are nothing new to Pelosi, who has faced token Republican opposition in most of her November races, along with occasional primary challenges. But since she beat former San Francisco Supervisor Harry Britt in the 1987 special election to replace the late Rep. Sala Burton, Pelosi's political resume has been short of opponents anyone other than local political junkies has ever heard of.

Sheehan has name recognition, particularly for her Camp Casey crusade.

"I said last year that I was going to take a break (from the anti-war movement) and then come back," Sheehan said in an interview at her Mission Street campaign headquarters.

But when the president commuted White House aide Scooter Libby's prison sentence last summer, she said, she decided "that seeing George Bush impeached would be a victory for humanity."

Calls for impeachment from Sheehan and other progressives didn't move Pelosi, who already had declared that impeachment was "off the table" when it came to the Democratic congressional agenda.

"In this political environment, the speaker has to work for those things that are possible," said Brendan Daly, a spokesman for Pelosi.

An impeachment effort, he said, "would be divisive, we couldn't get the votes, and we would have to spend all our time on it."

There are plenty of congressional Democrats, especially in the Bay Area, who don't agree, including Reps. Lynn Woolsey, Barbara Lee and Pete Stark, along with other progressives, both in and out of office.

Impeachment isn't Sheehan's only concern. Pelosi's refusal to vote for an immediate end to the Iraq war and to support single-payer health care shows she's out of touch with San Francisco's progressive roots, Sheehan said.

"I'll represent everyone in San Francisco, not just the corporate elite," she said. "I'm working class, my family was working class, and we have struggled the same way our neighbors here in San Francisco have struggled."

There's nothing unusual about Pelosi taking fire from the left, said Daly, her spokesman, especially when the speaker has to be concerned not only about her district, but also about the party across the country.

Pelosi "has always been forceful about speaking her mind on issues like human rights in China and the war in Iraq," he said. "In San Francisco, there's always tension between the district and the leadership responsibility."

The speaker will get an early look at the unhappiness of the city's progressives, because she's being challenged by local activist Shirley Golub in the June 3 Democratic primary.

"I've just had the sense from people I've talked to that (Pelosi) hasn't done what people in the community want her to do," Golub said. "People now have a choice, and they haven't had a Democratic choice for a long, long time."

Despite the upbeat talk, Sheehan and Golub, along with Republican Dana Walsh and Libertarian Philip Berg in November, are the longest of longshots to give Pelosi even a moment's worry on election day. In a district where Democrats outnumber Republicans 56 percent to 10 percent and a state where incumbents almost never lose, a party leader like Pelosi has every right to be making plans for her next term in office.

The odds don't bother Sheehan, who has raised more than $100,000 for her race, most of it from outside the district.

"Even people who I won't represent are willing to back me, because they know what I'll do in office," she said. "Many people in San Francisco know me, and they know my persistence.

"If I get to Washington, I'll only be in office a couple weeks before Bush leaves, but I guarantee he'll know I'm there."