PHOENIX – Controversial Arizona sheriff Joe Arpaio, known for targeting illegal immigrants, fended off a strong challenge from a Phoenix police veteran on Tuesday to win a sixth four-year term.

Republican Arpaio, the 80-year-old lawman who styles himself “America’s Toughest Sheriff,” claimed victory over Democratic challenger Paul Penzone to hold on to office as sheriff of Maricopa County. An unofficial county tally showed Arpaio nearly 11 points ahead with 596 of 724 precincts reporting.

The battle for the sheriff’s badge in Arizona’s most populous county highlighted bitter national divisions over illegal immigration.

“The president … is going after me, but I will continue to enforce the laws, including illegal immigration. Nothing changes,” Arpaio told cheering supporters late on Tuesday, vowing to continue his drive to lock up illegals.

The sheriff is the target of an ongoing Justice Department lawsuit alleging civil rights abuses by his office, including accusations of widespread racial profiling of Latinos in dozens of immigration “sweeps.”

The sheriff won support from Phoenix area conservatives for tough measures, including locking up county inmates in a Spartan “Tent City” jail and mounting a probe of Democratic President Barack Obama’s Hawaiian birth certificate.

Earlier this year, Arpaio dispatched a volunteer posse to Hawaii to investigate the authenticity of Obama’s birth certificate at the request of local Tea Party activists – a key Arpaio constituency.

He ultimately declared the document a forgery even after most Republican critics of Obama had given up pursuing discredited claims that the president was born abroad.

Rival Penzone, who had a 21-year-career with the Phoenix police department, gave Arpaio his toughest race yet, drawing on support from Latinos in the Phoenix area angered by what they saw as the sheriff’s relentless profiling of brown-skinned Hispanics in this sprawling metropolis. Arpaio has denied racial profiling.

There are also questions over what critics describe as the neglect of more than 400 sex-crime cases in a Phoenix suburb, some involving children.

Penzone told supporters that the scrutiny of Arpaio’s actions will not stop with the sheriff’s victory.

“He needs to know most importantly that the people of this community are going to be watching,” Penzone said. “They’re going to be holding him accountable.”

(Reporting by Tim Gaynor; Editing by Cynthia Johnston and Ciro Scotti)