CRAWFORD, Texas — Six weeks after announcing her departure from the peace movement, Cindy Sheehan said Sunday that she plans to run against the House speaker, Nancy Pelosi, unless she introduces articles of impeachment against President Bush in the next two weeks.

Ms. Sheehan said she will run against the San Francisco Democrat in 2008 as an independent if Ms. Pelosi does not seek by July 23 to impeach Mr. Bush. That’s when Ms. Sheehan and her supporters are to arrive in Washington, D.C., after a 13-day caravan and walking tour starting next week from the group’s war protest site near Mr. Bush’s Crawford ranch.

“Democrats and Americans feel betrayed by the Democratic leadership,” Ms. Sheehan said. “We hired them to bring an end to the war. I’m not too far from San Francisco, so it wouldn’t be too big of a move for me. I would give her a run for her money.”

Messages left with Ms. Pelosi’s staff were not immediately returned.

Ms. Sheehan announced in May that she was leaving the anti-war movement and selling her 5-acre Crawford lot. She said that she felt her efforts had been in vain and that she had endured smear tactics and hatred from the left, as well as the right.

She plans to make her official announcement Tuesday after what is expected to be her final weekend at the Crawford lot, which she sold to California radio talk show host Bree Walker.

Ms. Sheehan first came to Crawford in August 2005 during a Bush vacation, demanding to talk to him about the war that killed her son Casey in 2004.

She became the face of the anti-war movement during her 26-day roadside vigil, which was joined by thousands. But it also drew counterprotests of Bush supporters, many who said she was hurting troop morale.

Ms. Sheehan, who has never held political office, recently said that she was leaving the Democratic Party because it “caved” in to the president. Last week, she announced her caravan to Washington, D.C., which she calls the “people’s accountability movement.”

“I didn’t expect to be back so soon, but the focus is different than it was before,” Ms. Sheehan said Sunday. “Instead of talking and making accusations, we’re going into communities and talking to the people who’ve been hurt by the Bush regime. We’re finding out how we can help people.”

Ms. Sheehan said she lives in a suburb of Sacramento but declined to disclose the city, citing safety reasons.