A 73-year-old retired surgeon marching in silence with a tombstone picturing a soldier killed in Iraq. A philosophy professor calling for a new investigation into the Sept. 11 terrorist attacks. A long-haul trucker from Texas protesting the price of oil.

Those are just a few of the images that demonstrators hope will capture the attention of delegates, journalists and others attending the Republican National Convention. Tens of thousands _ from anarchists and immigrants to advocates for the poor _ plan to use the streets outside the Xcel Center as a national podium, transforming downtown St. Paul into a marketplace of ideas.

"There are some groups that are going to be here just because this is a big stage," said Chuck Samuelson, executive director of the American Civil Liberties Union of Minnesota. "But I think the majority of groups are here because they really want to demonstrate to the delegates that they want to see some sort of changes in the party platform."

Protesters and police expect the opening day of the four-day convention, Sept. 1-4, to be the biggest _ with a huge anti-war march from the state Capitol to the Xcel Center and back. Groups representing labor, immigrants, gays and lesbians, solidarity with Palestine, and many other causes have signed on.

"The Bush agenda has really angered all different groups," said Meredith Aby, a member of the Coalition to March on the RNC and Stop the War. "These groups have said, 'We can't survive four more years of this.'"

President Bush, whose approval rating was just 28 percent in a recent Associated Press-Ipsos poll, is scheduled to speak that night.

The war probably will generate a bigger turnout of demonstrators for the Republicans than the Democrats, who open their convention Aug. 25 in Denver, said Paula O'Loughlin, an associate professor of political science at the University of Minnesota-Morris.

"It is something that really gets people out in the streets," she said.

Democratic conventions have historically attracted more protesters. That tide shifted in 2004, O'Loughlin said, when more than 100,000 protesters _ likely a record turnout _ descended on the streets of Manhattan for the GOP convention.

At the Democrats' meeting that year in Boston, the largest protest came the day before it opened when about 2,000 anti-war activists and 1,000 abortion opponents marched separately.

The women and men of the anti-war group CODEPINK plan to join the march in St. Paul, complete with pink "police" on in-line skates and the pink-slip girls, who have been known to deliver their "pink slips" to politicians whom they believe aren't doing enough to end the war in Iraq.

The Red Wing chapter of Veterans for Peace is planning a smaller event on Aug. 31, the day before the convention begins. The group will walk in silence, to a beating drum, with each person carrying a tombstone picturing a civilian or soldier killed in Iraq. A group with orange jumpsuits and masks will represent the Guantanamo Bay prisoners.

"It's not directed specifically against the Republicans, that's for certain," said Red Wing's David Harris. "It's against the warmakers. But even people marching don't necessarily have to see things as broadly as I do."

Some of the messages converging in St. Paul are quite focused _ and as diverse as the messengers themselves:

_Tom Burke, a coordinator for Colombia Action Network, said his group will speak out against Plan Colombia, the multibillion-dollar U.S. aid package to help Colombia fight its war on drugs. His group says the plan is hurting peasants.

_New York artist Sharon Hayes will gather 100 people from the Gay, Lesbian, Bisexual and Transgender community to read a text that uses metaphor to discuss the ideas of personal and political desire.

_The Poor People's Economic Human Rights Campaign will host a "March for Our Lives" on Sept. 2. Cheri Honkala, the group's national organizer, said the group is multiracial, intergenerational, urban and rural. "People are just not surviving these economic times," she said.

_Attorney Martha Ballou's group, True Blue Minnesota, has rented two giant TV screens to bring "protest into the 21st century." The large video screens will blare images all day and all night while the convention is in town, Ballou said.

_The Genocide Intervention Network of Minnesota plans to set up a mock refugee camp to highlight violence in Darfur.

Between 3,000 and 3,500 police officers, sheriffs' deputies and state patrol officers are scheduled to work during the convention. Federal security officials will also be present.

Still, some groups are aiming for chaos. The RNC Welcoming Committee, on its Web site and e-mails to members, lays out strategies to block roads and use other methods to "crash the convention." Group members contacted by The Associated Press declined to be interviewed.

Those plans have caused unease among some who plan to demonstrate. Others say they are energized and angry over the war, phone tapping, tortured prisoners and the poor response to Hurricane Katrina.

"This is a big deal and a time we want to interject the voice of the people," said Joe Callahan, a Minneapolis bus driver and union member. "Now it's our turn."