Sunday's demonstration drew 7,000 to 10,000 people, rivaling the numbers in a similar event in mega-metropolis Los Angeles and underscoring Sonoma County's place in the debate.

Such turnouts in general could play a pivotal role in shaping public opinion and influencing lawmakers, those on all sides of the issue say.

"It gives not just the public but the people who shape public opinion and elected officials the sense that there is a movement under way, in a country where we have a history of public demonstrations," said Mark Baldassare, president of the nonpartisan Public Policy Institute of California.

Despite inflamed passions, Baldassare said this could be the year when Congress is moved to enact some form of comprehensive immigration overhaul.

"One of the things the voters have been saying is that they want the Republican president and a Democratic Congress to find solutions," he said. "This is an area where there could potentially be some movement."

For the second straight year, marchers jammed streets from Roseland to Juilliard Park, waving flags, beating drums and chanting support for immigrant rights.

Many who participated in 2006 were motivated by a Senate bill that would have required employers to check their workers' immigration status. The bill failed, and organizers of this year's event are hoping to have a similar influence in the national debate.

"We were able to come out and show our disgust with that bill," said Roberto Garcia, contract administrator for the United Farm Workers union. "We're still knocking on the doors of Congress, saying, 'Hey, you know what? We're not done yet.' We still need some type of just immigration reform."

He said the large turnout in Santa Rosa reflects Sonoma County's agricultural economy, which relies heavily on field workers, many of them undocumented.

But some wonder whether marches are enough to get their message out. Sunday's rally in Los Angeles drew an estimated 5,000 people to the city's Sports Arena, far fewer than the half-million who clogged the area last year.

"I think it's going to take local pressure campaigns, along with community education forums, so that not only the community is educated but also the politicians," said Davin Cardenas, an organizer with the Graton Day Labor Center, part of the Coalition for Immigrant Rights.

Groups opposed to immigrant rights, including the Minuteman Project, which seeks stricter law enforcement and border controls, are planning counter-demonstrations in coming weeks.

"We are fearful that the politicians in Washington, D.C., will look at the illegal aliens that are here as a voting bloc," said Tim Bueler, national spokesman for the project. Politicians "seem to pander to any immigrant rights group out there to get their vote."

Bueler, 20, a Rancho Cotate High School graduate, drew national media attention after starting the school's Conservative Club. He predicted upcoming demonstrations could become heated.

"As illegal aliens get more rights and Americans lose jobs, you're going to see more outrage, and if violence occurs, that's a sign of the times," he said.

Others, however, say the more likely outcome will be centered on compromise.

"I think there is broad areas of agreement and looking for some workable solutions to the fact there are large numbers of immigrants, legal and illegal, that are part of the economic fabric of this country," Baldassare said.

Rep. Lynn Woolsey, D-Woolsey, said she hopes an immigration package is enacted this year ahead of the 2008 presidential race, when consensus could be harder to reach.

She placed the onus on President Bush to get the ball rolling.

"The first step should be the president laying out his immigration plan," Woolsey said. "It really does no good to go through all the dance and have him veto it."