At least 200,000 mostly Hispanic demonstrators protested in California on Saturday against moves to tighten US immigration laws, while President George W Bush urged wary Republicans to take up his guest-worker proposal.
A boisterous crowd, many wearing the red and green of the Mexican flag, packed the streets in front of Los Angeles City Hall to protest Republican bills they say would hurt the estimated 12 million illegal immigrants in the United States.
The bill, which has already passed the US House of Representatives, would make it a federal crime, instead of a civil offence, for undocumented workers to live in the country and would penalise people who help illegal immigrants. The Senate will take up the immigration issue next week.
Protester Eduardo Sotelo Piolin, a disc jockey with La Nueva radio, said he opposed the tough measures.
"I am one of thousands of people who crossed the border in the trunk of a car because I wanted a better life," he said. "Today, I'm a documented worker. But we should respect the people who are not documented and we should not treat them like criminals."
Protest organisers estimated the crowd at one million, but police spokeswoman Sara Faden put the numbers at 200,000.
Speakers took turns at a podium at the foot of the steps to City Hall, giving speeches mainly in Spanish. A live band with drums, guitars and trumpets played music nearby.
Some demonstrators carried home-made paper signs. One read: "Illegal immigrants are welcome to go to war, but why can't we have a job, home or licence?"
Bush pushed his plan for a guest-worker plan and better border enforcement in his weekly radio address on Saturday.
Some Republicans oppose the guest-worker plan as a backdoor amnesty for illegal immigrants and prefer an approach that focuses solely on toughening border security and cracking down on illegal immigration.
The guest-worker program could attract Hispanic voters in key states like Arizona, New Mexico and Florida.
Senate Judiciary Committee Chairman Arlen Specter, a Pennsylvania Republican, wants to finish work on legislation that includes a temporary worker program and would give undocumented aliens an opportunity to legalise their status.