Arapaio says he's definitely seeking a sixth term as the county's top lawman. He formally announced his plans on Thursday to seek re-election in November, though he has said repeatedly over the last two years that he will run again.
The campaign says Arpaio has raised $6 million in campaign money.
Scottsdale police Lt. Mike Stauffer is challenging Arpaio. Stauffer is an Independent, while Arpaio is a Republican.
Arpaio has refused recent calls from some of his critics to resign because of allegations that his office racially profiles Latinos and didn't adequately investigate hundreds of sex-crimes cases.
The controversial Arizona sheriff accused of a long list of civil rights violations conditionally agreed Wednesday to discuss with federal officials ways to correct the alleged violations.
Maricopa County Sheriff Joe Arpaio said that his office first needs the U.S. Justice Department to provide facts to back up its allegations that his office racially profiles Latinos, bases immigration enforcement on racially charged citizen complaints and punishes Hispanic jail inmates for speaking Spanish.
"I have a suspicion that politics might be involved in this, but we want to resolve (the case)," Arpaio said.
Joseph Popolizio, one of the lawyers representing the sheriff's office, said in a letter to Justice officials that Arpaio was ready to go to court if federal authorities refuse to provide the information to back up their claims.
The self-proclaimed toughest sheriff in America has been a national political fixture who has built his reputation on jailing inmates in tents and dressing them in pink underwear, selling himself to voters as unceasingly tough on crime and pushing the bounds of how far local police can go to confront illegal immigration.
The sheriff's office said it doesn't discriminate against Latinos and that Justice Department didn't provide facts to support its allegation that Arpaio's office has a culture of disregard for basic constitutional rights.
Based on reporting by the Associated Press