Joe Arpaio, the longtime Maricopa County (AZ) sheriff and a political ally of President Trump, will run in the 2018 Republican primary to replace Sen. Jeff Flake (R-Ariz.), who is retiring.
Former Sheriff Joe Arpaio Running for Senate
Arpaio, who has frequently talked about seeking higher office, said he decided to run as a “big supporter of President Trump” who would back the president wholeheartedly.

Arpaio, 85, made the bid official in an interview with the Washington Examiner .
Arpaio, who has frequently talked about seeking higher office, said he decided to run as a “big supporter of President Trump” who would back the president wholeheartedly. He is entering a primary against Kelli Ward, a former state senator also running as a Trump ally. His decision may create an opening for Rep. Martha McSally (R-Ariz.), a Republican with more moderate views who is contemplating a bid for the seat and is backed by party leaders in Washington, the Washington Post reports.