Maricopa County Sheriff Joe Arpaio known for aggressively cracking down on illegal immigration has been stripped of some of his special power to enforce federal immigration law, as a result of racial profiling allegations over crime and immigration sweeps in some heavily Latino areas of metro Phoenix. He claims the Obama administration is taking away his authority for political reasons.

Homeland Security officials declined to comment, saying they are still reviewing their agreement with the sheriff’s department and the other 65 agencies that participate in a program that allows local and state officers to make immigration arrests.

Immigrant advocates and some lawmakers have called on the department to end the program, known as 287(g) after the section of the 1996 law that authorized it, saying it has led to racial profiling and other abuses. Nationally, more than 1,000 local police and jail officers have been granted the power since 2002 to make immigration requests and speed up deportations. The Homeland Security Department has sought to mend it the program, not end it.

His office is being investigated by the U.S. Department of Justice over allegations of discrimination and unconstitutional searches and seizures.