"Sheriff Joe is one of the very few guys who will enforce the immigration laws across this nation," said Randy Hatch, who used a megaphone to rally supporters of Arpaio at a park in this northeast Phoenix valley city.

"Every constitution and country that has ever existed has had to have sovereign borders," he said to cheers from the crowd, some clutching placards reading "Sheriff Joe keeps us safe" and "illegal is illegal."

Arpaio, who styles himself "America's toughest sheriff," is a resident of Fountain Hills.

Earlier this month the Obama administration said it was preparing to sue Arpaio and his department "for violating civil rights laws by improperly targeting Latinos."

The sheriff has denied any wrongdoing and lashed out at the federal government for targeting his department while failing to confront the more than 11 million illegal immigrants who live and work throughout the nation.