The Obama administration is suing Arizona over the state's strict new immigration law as the White House attempted to wrestle back control over the issue but infuriating Republicans who said the border required more security.
The administration argued the Arizona law, which requires state and local police to investigate the immigration status of anyone they reasonably suspect of being an illegal immigrant, is unconstitutional and would sap law enforcement resources.
The Republican-controlled Arizona legislature passed the controversial law to try to stem the flood of thousands of illegal immigrants who cross its border from Mexico and to cut down on drug trafficking and other crimes in the area.
The lawsuit is part of a broader approach by President Barack Obama to deal with the 10.8 million illegal immigrants believed to be in the country, arguing that immigration is the responsibility of the federal government not each state.
"Seeking to address the issue through a patchwork of state laws will only create more problems than it solves," US Attorney General Eric Holder, said in a statement.
The legal action, filed while Congress was on a week-long break, is a political gamble by the administration as a Pew Research Center poll showed 59 per cent of people approve of the Arizona crackdown.
The legal fight also comes at a critical juncture, four months ahead of the mid-term congressional elections, and the Hispanic community has been a major voting bloc that typically has sided with Democrats but Republicans have tried to woo.
The Justice Department filed the lawsuit in federal court in Arizona and asked for an injunction to prevent the law from taking effect on July 29th.
Arizona Governor Jan Brewer condemned the lawsuit as a waste of taxpayer funds and said the state law was needed because the federal government had not done its job.
"As a direct result of failed and inconsistent federal enforcement, Arizona is under attack from violent Mexican drug and immigrant smuggling cartels. Now, Arizona is under attack in federal court from President Obama and his Department of Justice," Ms Brewer, a Republican, said in a statement.
She vowed to fight the lawsuit and said she had set up a legal defence fund to cover legal fees stemming from the federal challenge and other lawsuits.
The Justice Department acknowledged that Arizona legislators had "legitimate concerns" about illegal immigration but noted the US Constitution gave the federal government sole authority over immigration matters.
Reuters