Tens of thousands of demonstrators in more than 70 U.S. cities turned out over the weekend in protest of a new Arizona immigration law, which has re-ignited the simmering national debate over immigration policy.

People attend a grand rally demanding immigrants and labors rights in downtown Los Angeles, the United States, May 1, 2010. [Xinhua]

Arizona has enacted a law that demonstrators described as Draconian and racist, as the legislation requires police officers in the border state to question suspects about their immigration status if there is "reasonable suspicion" that the individual may be staying in the United States illegally.

It would also require immigrants to carry documents proving they are legal.

The law's supporters counter that the federal government has failed to protect U.S. borders and that state lawmakers had little choice but to enact the measure, pointing out the March killing of Arizona rancher Robert Krentz, which authorities linked to drug runners crossing into the United States from Mexico.

U.S. President Barack Obama vowed to overhaul the nation's immigration policy in the run-up to his election, and his reforms would include a path to citizenship for many of the 12 million illegal immigrants living in the United States.

The proposal is a controversial measure to many on the right, as well as a number of legal immigrants who waited in line for years and paid thousands of dollars in lawyers' and paperwork fees.

Many undocumented workers, in contrast, argue they make significant contributions to the U.S. economy and have earned legitimacy.

Darrell M. West, vice president and director of governance studies at the Brookings Institution think tank, said the protests will put pressure on elected officials to take action on immigration because Latinos are a large and growing voting bloc.

"No one really likes the status quo and there are increasing calls for the federal government to take action in this area," he said.

Congress chimed in on the debate on Thursday, when Senate Majority Leader Harry Reid proposed a measure that would heighten border security and provide a path to citizenship to some of the estimated 12 million illegal immigrants living in the United States.