Thousands of activists rallied in Lower Manhattan Saturday to protest Arizona's controversial new immigration law.

"It is time for immigration reform and its time for it now!" chanted union members, as they mobilized simultaneously in Foley Square and Union Square. Many carried banners denouncing the measure, which requires law enforcement to question people about their immigration status if there's suspicion they may be staying in the U.S. illegally.

"I was born in the United States, but now I'm afraid if I go to Arizona, I'll have to carry a birth certificate because I don't fit the typical American picture," said NYU student, Samuel Chun.

Without federal regulation in place to address the estimated 12 million illegal immigrants living in the U.S., many fear other states will follow Arizona's lead.

"Our big fear is that Arizona could start a trend, and we're here to say there's more of us here in this country that are against the Arizona proposal," added Bhairavi Desai of New York's Taxi Workers Alliance.

"People are here. They're working, they're paying taxes, they're contributing to the economy in many ways," said Ramona Ortega, an immigration rights advocate. "We depend on them."

"Let them pay a fine or something, and straighten out the papers and make them citizens," suggested Louis Gomez, a Local Union 79 member.

Meanwhile, a small group of protesters across from Union Square voiced their support for Arizona's law. They say the law is necessary because of slipping border control, and growing anxiety over crime related to illegal immigration.

"The federal government recently failed Arizona in securing the border... just like the federal government failed New York and the rest of the states," said Joanna Marzullo of New Yorkers for Immigration Control and Enforcement. "So Arizona took matters into its own hands and I hope New York follows suit."

But, critics don't seem to be backing down. They're convinced the law is unconstitutional and encourages racial profiling and discrimination against immigrants or anyone thought to be an immigrant. As a result, more protests and expected to follow.