Updated

As many as 100 cities across the country served as hosts Monday to rallies and protests against any get-tough measures federal lawmakers are considering to crack down on illegal immigration.

Protests were held in cities such as Philadelphia, Washington, D.C., Atlanta and Phoenix, and Texas cities such as Houston, Austin and El Paso. In North Carolina and Dallas, immigrant groups called for an economic boycott to show their financial impact. Rally participants sang "We Shall Overcome" in Spanish at the Mississippi Capitol in Jackson.

Organizers urged demonstrators to coordinate their outfits by wearing white T-shirts to symbolize peace and a "campaign for immigrants' dignity." At the Hispanic shopping mall, Plaza Fiesta, in Atlanta, many demonstrators had emblazoned on their t-shirts the Spanish words for "Legalization, yes you can." Many families brought their children in strollers.

Atlanta police estimated at least 50,000 people joined a two-mile march from a largely immigrant neighborhood Monday morning.

Unlike earlier protests in Los Angeles and other cities when protestors waved flags from Mexico and other countries, activists Monday around the country waved American flags, an obvious response to criticism that illegal immigrants aren't interested in assimilating into American culture and have no allegiance to this nation.

Two prominent Democrats joined rallies to help prod immigration reform through Congress after one such effort stalled in the Senate late last week; any reform plans are on hold until the Senate returns from its Easter recess in two weeks. In addition to national legislation, a Georgia law that awaits signature by Gov. Sonny Perdue, would force immigrants to prove legal residency before receiving some state benefits.

New York Democratic Sens. Hillary Clinton and Charles Schumer joined a rally in New York City, while Sen. Edward Kennedy, D-Mass. — one of the chief architects of the current reform bill before the Senate — spoke to tens of thousands of demonstrators in the nation's capital.

"I look across this historic gathering and I see the future of America. As President Kennedy proclaimed a half century ago, we are a nation of immigrants. And today, we stand together as brothers and sisters to shape America's destiny — old Americans, new Americans, future Americans — all joined together for the common good," Kennedy said after speaking a few sentences of Massachusetts-accented Spanish.

"Even more than thanking you for being here, thank you for the work you do every single day. Thank you for being part of what makes our economy work," Clinton told the crowds that had marched across the Brooklyn Bridge.

'If They Won't Take the Job, What's the Problem?'

During Monday's protests, Carlos Carrera, a construction worker from Mexico now residing in the Atlanta area, held a large banner that read: "We are not criminals. Give us a chance for a better life."

"We would like them to let us work with dignity. We want to progress along with this country," said Carrera, who said he has been in the United States for 20 years.

Elsa Rodriguez, 25, talked about the baby girl she expected to give birth to in about three months.

"This is why I had to be here," she said. "She's going to be a U.S. citizen and I'm here illegal?"

In Pittsburgh, a smaller group marched to Sen. Arlen Specter's district office. The Republican senator has advocated a bill in the Senate that would support a guest worker program, unlike a bill from the House that critics say would clamp down on illegal immigrants, their employers and others who assist them.

"We all know pay is not the same everywhere and a lot of people won't work for the minimum here, so if they won't take the job, what's the problem?" said 47-year-old Jose Salazar, who was protesting in Pittsburgh.

"This country was built by immigrants, Pittsburgh in particular," said Yinka Aganga Williams, 54, who came from Nigeria six years ago. "This is supposed to be a land of freedom, that's why they came."

An event in Harrisburg, Pa., drew a handful of hecklers.

"Go to jail!" shouted William Hazzard, 58, a retired school custodian from Harrisburg. "I'm from Germany and I had to give up my rights as a German citizen. I had to speak English."

Raymond Marks, 47, an apartment complex service manager, held an upside-down American flag as a sign of distress.

"These people are expecting me to give them rights they don't deserve," he said.

In Salt Lake City, Jerry Owens, 59, a Navy veteran from Midway wearing a blue Minuteman Project T-shirt and camouflage pants, held a yellow "Don't Tread on Me" flag.

"I think it's real sad because these people are really saying it's OK to be illegal aliens," Owens said. "What Americans are saying is 'Yes, come here. But come here legally.' And I think that's the big problem."

Rep. Tom Tancredo, R-Colo., a leading congressional voice against illegal immigration, said the guest worker plan advocated by some in the Senate amounts to an amnesty for illegal aliens who have disregarded U.S. laws and values.

"Amnesty is an affront to American law and America's tradition of legal immigration," Tancredo said. "If the protesters really want to honor America's values, they would stand up to lawbreakers and embrace an enforcement-first approach to fixing our broken system."

In California, 16 protests were planned. An estimated 3,000 people demonstrated in Garden City, Kan., a farming community in the southwest corner of the state that counts fewer than 30,000 residents. Several hundred turned out in South Bend, Ind., and in Lexington, Ky., where they waved signs that read: "We were all immigrants once," and "We are not terrorists."

Hundreds of Latinos in North Carolina prepared to skip work or boycott all purchases on Monday to demonstrate the financial impact of the Latino community on area businesses. In Charlotte, some employees planned to skip work, including some with the blessing of their Latino bosses.

"We're hoping that employers stop to consider what this is all about," organizer Adriana Galvez said. "That if you need people here to do the work, to buy, then give them a legal channel to get here."

Cruz Luna, his wife and their four children all wore T-shirts reading "God Bless America" at a demonstration in Pensacola, Fla. The two oldest children — ages 8 and 9 — were born in Mexico and are in the U.S. illegally; their younger siblings, ages 4 years and 8 months old are U.S. citizens.

"We want to send a strong message today, a message that we want the laws to be fair," Luna said

As many as 100,000 illegal immigrant rights supporters marched in Phoenix. Marchers began at the Arizona State Fairgrounds and rallied at the state Capitol, where state lawmakers this year are considering dozens of immigration bills.

In Phoenix, Miguel Penate, a fast-food restaurant manager who moved from El Salvador six years ago, said being in the country illegally was his only option.

"There's no way to come legally over here," said Penate, 25. "If there was, do you think people would like to be in the desert risking their lives?"

Thousands more were expected to rally in Tucson, where several hundred had already gathered near a church by early Monday morning. Some carried American flags. Others wore T-shirts that said: "We are not the enemy, we are part of the solution."

"We want justice, that's what we want, and make it fair for the people coming from the other side," said Lupita Lopez, one of the Tucson marchers.

Arizona, the busiest illegal entry point along the nation's porous southern border, is home to an estimated 500,000 illegal immigrants out of the state's population of about 6 million.

Monday's demonstrations followed a day of rallies in 10 states, including up to 500,000 people in Dallas, 50,000 in San Diego, and 20,000 in Salt Lake City. Dozens of rallies and student walkouts, many of them organized by Spanish-language radio DJs over the past few weeks, have been held in cities around the country, from Los Angeles to Chicago to New York.

The protests are aimed, in part, at defeating one immigration reform bill that already has approval from the House. In addition to stiffer criminal penalties, H.R. 4437, also known by the name of its chief sponsor, Rep. James Sensenbrenner, R-Wis., contains tougher border security measures, including a proposal for a 700-mile fence along the U.S.-Mexico border.

One proposal the Sensenbrenner bill does not contain is the guest worker program that President Bush prefers. Bush supports allowing some illegal immigrants who do not have criminal backgrounds to stay for a certain amount of time in the country and work legally.

"We want to stop HR4437 and we are demanding the Senate go back to the drawing board and develop an immigration reform bill and really fix the problem," said Juan Carlos Ruiz, national coordinator for the National Capital Immigrant Coalition. "We want to be part of the solution to make this country better."

Speaking before a student audience in Washington on Monday, Bush told one person in the audience that while borders need to be secure, it's also important to give some immigrants a break "so they don’t have to try to sneak across the border. ... If they want to become a citizen after a series of steps they've got to take, they get in line, not ahead of the line."

A Senate compromise reached last week amidst partisan bickering would contain a guest worker program, but would give greater access to citizenship to those who have been residing in the United States longer than five years. Another group — those who have lived here between two and five years — would face more restrictions, but could stay here and in time apply for citizenship. Those here fewer than two years would have to leave the country and apply for legal entry.

But that compromise fell apart Friday. Specter, chairman of the Senate Judiciary Committee, says the bill will be his committee's top priority.

Republican strategist Michelle Laxalt said it's not clear whether the protests will have the desired effect.

"It depends on who is demonstrating and where. I'm not sure whether or not the demonstrators in some states are saying the same thing that demonstrators in other states are. That is I think something that each member [of the Senate] is going to be listening very carefully to what happens in the next two weeks while they're in recess," she said.

Doug Schoen, a Democratic strategist and FOX News contributor, suggested the protesters could only help themselves.

"Who knew that there would be millions of people out in the street wearing white T-shirts, waving the American flag, saying, 'We are part of America?' ... What they are saying is they are a part of American society ... and they want both citizenship rights and they want a process to become part of America," Schoen said.

Over the weekend, the crowd estimates at a Dallas rally were anywhere between 350,000 and 500,000. Another 20,000 were said to have appeared in Salt Lake City. More rallies were held in San Diego, Minnesota, New Mexico, Michigan, Iowa, Alabama, Oregon and Idaho.

The Associated Press contributed to this report.