The antiwar rally here Saturday began much the same way as a half-dozen others before it, with thousands of placard-carrying protesters marching through the streets. But this one was also noticeably different.

Among the crowd of a few thousand, there were clear signs that war protesters are embarking on a new phase. Many more of the protesters' placards took aim directly at President Bush: "Bush Must Go!" "Impeach Bush!" Voter registration tables urging protesters to "Vote for change!" also dotted the city park that served as the rallying point.

Although this demonstration, like the others across the country Saturday, was set before Baghdad crumbled, antiwar organizers said they were already preparing to shift their attention beyond protesting the war to a more ambitious agenda. In broad terms, according to leaders of some of the largest national peace groups, the antiwar movement is reshaping itself to become an anti-Bush movement.

Just how the antiwar movement plans on challenging the president depends on which group you ask. Some are focusing on registering voters to challenge Bush in 2004. Others say their emphasis will be on finding congressional candidates to run against those who have supported or acquiesced to the Bush administration. Still others say they will emphasize creating permanent community-based groups that will fight the administration's policies. Some also say that while they plot their next big moves, they will continue to hold teach-ins, protests and other forums to criticize the current military policies and practices in Washington and fortify their ranks.

But antiwar organizers (or, as many prefer to be called these days, "peace" organizers) acknowledge that their mission is tricky. Bush's approval ratings have climbed, and the movement has suffered a setback since the invasion of Iraq. As a majority of Americans (up to 70 percent, according to some polls) rallied behind the war, many considered dissent an affront to the troops risking their lives. In the few weeks since the war began, hostility toward antiwar expressions has skyrocketed. Celebrities who have spoken out against the war have been booed off stages and removed from public appearance rosters. Politicians who have criticized the administration have been called traitors. War protesters across the country have reported death threats.

Bush strategists looking ahead to the 2004 election say they plan to parlay the president's postwar political momentum into a successful domestic agenda, positioning him for reelection. Antiwar organizers, many of whom were critics of the administration from the beginning, say they plan to point out the terrible costs of the war, even a short one, on human life; the bottomless military budget at a time of burgeoning budget deficits; and the costs of the administration's military policies in terms of international goodwill.

But Melvin Small, a history professor at Wayne State University in Detroit and author of "Anti-Warriors: The Vietnam War and the Struggle for America's Hearts and Minds," said the antiwar movement is in a difficult spot. "In terms of numbers, it has been wildly effective," he said, "lots of people on the streets and lots of media coverage. But in other ways, it was not effective. Our administration didn't seem to care about many people on the streets. . . . And it's very difficult to get people to oppose war when they can see their heroic boys and girls fighting for the U.S. on 24-hour television."

Michael Negler, who teaches in the Peace and Conflict Studies department at the University of California at Berkeley and who has written extensively on nonviolent protest, said the current antiwar campaign "hasn't been as effective as it could be." Whether nonviolent civil disobedience actions at military installations and corporations that stand to profit from the war will have an effect remains to be seen, he added. "In nonviolence, we don't always judge by immediate results," Negler said. "Nonviolence is confident it will have positive effects down the line."

But even here in San Francisco, the heart of the antiwar movement, the public seems to be wearying of protests, especially those that disrupt their daily lives and cost the financially ailing city millions of dollars in police overtime.

Peace groups say the immediate challenge is to keep the people who were against the war before it began from disengaging. Andrea Buffa, co-chairman of United for Peace and Justice, one of the largest national antiwar coalitions, representing more than 200 organizations, said given recent events, many peace groups across the country are discussing their next moves.

"The peace movement is at a critical juncture," she said. "Although most peace activists understand that cheering about the demise of Saddam Hussein isn't the same as Iraqis saying they support the war -- or, much less, a U.S. occupation of their country -- we know that many Americans don't make this distinction."

But several antiwar leaders said their plans don't rely on the daily headlines of the war. Michael Kieschnick, president of Working Assets, the long-distance, wireless and credit card company that donates a percentage of its sales to social causes, plans on a massive voter registration campaign through its advocacy arm, Working for Change. "It's our goal to register a million voters for the 2004 election," Kieschnick said. "That is going to be our main thrust -- to take the millions of people who say they oppose this war and the philosophy behind it and turn it into voting power."

The group has launched a humanitarian fund for relief and also, Kieschnick said, "to try to build democratic, grass-roots organizations in Iraq of which there are essentially none right now." It is also planning a campaign for its 700,000 members to challenge and try to change the U.S. doctrine of preemptive strikes, he said. "It's one thing to criticize this war," he said, "and it's quite another to turn back the clock on this dangerous doctrine."

Other groups that are concentrating on registering voters include Black Voices for Peace, which aims to capitalize on polls that show support for the war was lowest among African Americans.

"We are organizing to do voter registration and education because, in our view, this is the most dangerous administration that has ever been assembled in our history," said Damu Smith, the organization's director. "We are working on trying to build our national network to make sure that there is an unprecedented black turnout in the next election."

Some protest leaders say that although national attention for the moment is focused on the toppling of Hussein's government, the euphoria of military victory will fade, as it did for President George H.W. Bush after the 1991 Persian Gulf War.

"I'm pleased that only 70 percent of the country supports the administration," said Bob Edgar, general secretary of the National Council of Churches and co-chairman of the Win Without War coalition. "During the Vietnam War there was a 90 to 95 percent approval for the war."

Edgar, a former Democratic House member from Pennsylvania, said his group hoped to groom candidates for Congress from the antiwar movement -- those who are so angry at the goings-on in Washington that they want to change things from the inside out. "One year before I got elected, I got mad at President Nixon," Edgar said. "Some of the young men and women who've gotten involved in fighting the first-strike policy need to step forward and challenge the Democratic and Republican candidates. If a few more Paul Wellstones don't get elected, you're going to have the mealy-mouthed Congress we have now."

The National Council of Churches, for its part, plans a meeting April 29-30 in Chicago for religious leaders from dozens of denominations, Edgar said. The session plans on addressing postwar issues such as urging that humanitarian aid be given through international non-governmental organizations.

Indeed, most national antiwar organizations say they plan on stressing the need to seek international participation in postwar Iraq, as well as international consensus before acting again.

Bill Hackwell, a spokesman for International ANSWER, the most left-wing of the major antiwar groups, said ANSWER plans on mobilizing people into an independent "grass-roots movement" similar to that formed during the Vietnam War.

"Our work is not in electoral politics," Hackwell said. "Just as the Vietnam War was brought to an end by the antiwar movement in conjunction with the civil rights movement, we can't pin our hopes on people running for office. The ability of Congress to vote for war has been abdicated. We have to teach the politicians to listen to the people who pay their salaries."

Despite the waning numbers in protests, Hackwell said ANSWER, which has organized many of the largest rallies, will probably organize more. "I don't think the demonstrations are going to go away," he said. "This is a period where the U.S., and to some extent, the media, are flush with this victory. But we don't look at it as a liberation, nor does most of the world."

Demonstrators in downtown Washington joined others nationwide Saturday in protesting the war in Iraq. Such groups are beginning to look beyond the war at a larger plan.Members of various religions place flowers on cloths to represent dead children in Iraq during an antiwar rally staged in front of the Federal Building in San Francisco. The event was called "Swords to Plowshares."