Dueling Protests: Face-Off Over Arizona Immigration Law Opponents march on state capitol, but backers of controversial law also gather.

PHOENIX, May 29, 2010  -- In their most massive numbers yet, a deluge of adversaries rallied and railed against what could soon be the law of the land in Arizona.

"This is the next civil rights movement, is what we believe," protester Vivian Nelson-Melle told ABC News.

Arriving by the busload, tens of thousands of people from around the country marched to the Arizona state capitol Saturday to protest the state's tough new crackdown on illegal immigration.

The new law mandates that police question suspected law breakers about their immigration status if there's a reasonable suspicion they're in the country illegally.

"This law reflects very poorly on Arizona. It makes us appear as if we're a bunch of racists here and we're not," protester Russ Becker said.

On Friday, the Justice Department hinted that the Obama administration is willing to sue to block the law from taking effect two months from now.

Arizona Attorney General Terry Goddard doesn't like that one bit.

"I told them we need solutions from Washington, not more lawsuits," Goddard said.

Boycotts Called 'a Violent Attack on Business Owners'

But there is support for the law now echoing across the country, with a handful of other states pondering their own immigration crackdowns.

Opponents of the new law weren't the only ones who rallied Saturday. Supporters of the law, including members of the Tea Party movement, gathered Saturday night at a Tempe baseball stadium. They were there to push a "boycott" of their own, to support businesses in Arizona.

"It's about spending your money in Arizona and being opposed to these boycotts, which are nothing more than a violent attack on business owners anyway," said Tony Katz, a Tea Party organizer.

Racial Profiling? Law's Foes Say They're Intimidated, Not Businesses

If anyone's being intimidated, opponents of the law say, it's them, because of the color of their skin.

In fact, there were a few counter demonstrators who showed up at Saturday's march on the state capitol, donning weapons and Confederate flags.

Arizona's new law is set to take effect at the end of July, barring a successful legal challenge.