With Congress on the verge of approving the use of force against Iraq, anti-war activists around the country are struggling to generate fervor for peace. 

On Sunday, thousands of protesters rallied in a dozen cities, with as many as 10,000 each in New York's Central Park, in San Francisco's Union Square and outside a federal building in Los Angeles. 

But most demonstrations around the country have been more modest in size, with turnout of no more than a few hundred people. 

"There's an inhibition about opposing American foreign policy, even where there's a strong conviction that it's badly mistaken," says Todd Gitlin, a Columbia University professor and author of The Sixties. "There's the general sense that we're at war -- we were attacked." 

Others note that it took years before protests against the Vietnam War gathered the critical mass to make the nation's leadership commit itself to pulling out. 

"An ocean is made up of one drop of water at a time -- peace movements start the same," Javed Chaudhri, a professor at Keene State College, told the crowd at a rally in Brattleboro, Vt. 

Still other observers of American protest movements are confident the anti-war cry is growing louder, even though the movement is scattered. 

"I'm more optimistic about my country now than any time in my entire life, because of the hundreds of thousands of smaller efforts," said folk singer Pete Seeger, who at 83 has shared the stage with generations of anti-war activists. "We don't all agree all the time, but we all agree it's better to talk than shoot." 

Recent polls show that a slight majority of Americans supports sending ground troops into Iraq to topple Saddam Hussein. However, a majority opposes unilateral U.S. action without allied help. 

Sunday's demonstrations were organized by the Not in Our Name coalition, a group that includes prominent intellectuals, civil-rights activists, authors, actors and others, among them Noam Chomsky, Gloria Steinem, Russell Banks, Susan Sarandon and Edward Said. 

Another citizen group, Common Cause, challenged Bush administration policy in a full-page newspaper ad signed by former anchorman Walter Cronkite, historian Arthur Schlesinger Jr., former New York Governor Mario Cuomo and others. 

Also, the U.S. Conference of Bishops wrote the president, saying a pre-emptive strike against Iraq is not justified. 

Nearly every major city has seen some protests. Some demonstrators have occupied federal offices, leading to arrests in Washington and Minnesota. 

Weekly vigils and silent protests have also been held, from Nebraskans for Peace, to Quakers in Baltimore and Albany, N.Y., to Catholics in St. Louis and Cleveland. Ithaca, N.Y., and Santa Cruz, Calif., passed resolutions against attacking Iraq. 

Marches scheduled for Oct. 26 in Washington, D.C., and San Francisco could be the biggest demonstrations yet. 

Many of the speakers at rallies around the country have stressed that Al Qaeda, not Iraq, was responsible for the Sept. 11 attacks, and warned that targeting Saddam Hussein now could spawn more terror attacks. 

"People stop and thank us for being brave, some people actually get out of their cars and join us," said Gary Gillespie, a spokesman for the Baltimore office of American Friends Service Committee, an international Quaker human-rights organization. "Occasionally someone yells at us, 'Bomb em!' But there are far more peace signs these days."