FILE - In this Thursday, May 10, 2012 file photo, United States Assistant Attorney General Thomas Perez, left, is joined by Deputy Assistant Attorney General for Civil Rights, Roy Austin, as Perez announces a federal civil lawsuit against Maricopa County Sheriff Joe Arpaio during a news conference in Phoenix. The White House says President Barack Obama on Monday, March 18, 2012 will nominate Perez to head the Labor Department. (AP Photo/Ross D. Franklin, File)