Updated: 2:04 p.m.

In the latest salvo aimed at Arizona’s tough new immigration law, civil rights and Hispanic advocacy groups announced Monday that they would jointly file a federal class action lawsuit challenging the constitutionality of the new statute.

The American Civil Liberties Union, the Mexican American Legal Defense and Educational Fund and the National Immigration Law Center are spearheading the legal challenge, which coalition representatives formally announced during a Monday afternoon conference call.

“This law turns ‘Show me your papers’ into the Arizona state motto and racial profiling into the Arizona state plan,” said Lucas Guttentag, director of the ACLU’s Immigrants’ Rights Project. Guttentag called the new law “the most extreme and dangerous of all the recent state and local laws purporting to deal with immigration issues.”

The lawsuit, filed Monday in the U.S. District Court of Arizona with 14 organizational and 10 individual plaintiffs, aims to forestall the law — now slated to take effect July 28 — from ever being implemented. It claims that the law violates the Constitution’s supremacy, equal protection and due process clauses, as well as the Fourth and First amendments and other provisions of federal law, including civil rights statutes.

Late last month, Attorney General Eric Holder raised the possibility that the Justice Department could join the fray with its own constitutional challenge to the law, which he said federal officials were in the process of reviewing. In the meantime, Latino advocacy groups have called on the Justice Department for help in staying implementation. Representatives of the groups that filed the lawsuit Monday said it was well past time for Obama administration officials to do something.

“It’s time for them not just to talk about those effects but to take action to prevent this law from going forward,” said National Immigration Law Center General Counsel Linton Joaquin, adding that it would be “totally appropriate” for federal government to press for an injunction preventing the law from taking effect.

“We have called on the federal government to step in to this case,” Joaquin said. “The federal government’s ability to do its job properly is being impeded for every moment that this law stands out there.”

Hispanic lawmakers and members of the Latino community have been in full-on battle mode since before Gov. Jan Brewer (R) signed the measure into law last month. They claim the new law — which makes it a crime to be in the country illegally and requires local law enforcement officers to question suspected illegal immigrants about their immigration status — will lead to widespread racial profiling and runs afoul of constitutional protections of civil liberties.

Nina Perales, southwest regional counsel for MALDEF, said Monday that the law would put local police in an “impossible position” because “an officer cannot form a reasonable suspicion about person’s immigration status just by looking at that person.”

But broader public opinion is running against the groups, according to an NBC-Wall Street Journal poll released last week. That poll found that nearly two-thirds of Americans favor the new law, which has led to new calls among lawmakers who back comprehensive immigration reform for Congressional action before November’s midterm elections.

On April 29, a group of Latino clergy and religious leaders and an Arizona police officer filed separate lawsuits — also in federal court in Arizona — challenging the law.