Controversial former sheriff Joe Arpaio is running in the open Senate race in Arizona, jumping into a Republican primary that is expected to be a contest over who is most closely aligned with President Donald Trump.

Arpaio said he was a “big supporter of President Trump” in an interview with the Washington Examiner, which first reported the news.

“I am running for the U.S. Senate from the Great State of Arizona, for one unwavering reason: to support the agenda and policies of President Donald Trump in his mission to Make America Great Again,” Arpaio tweeted Tuesday morning.

Trump pardoned Arpaio last year after the former Maricopa County sheriff was convicted of defying a court order in a racial profiling case.

Arpaio’s entrance in the race could complicate things for former state Sen. Kelli Ward, who had attempted to cast herself as the most pro-Trump candidate in the race.

GOP Rep. Martha McSally is expected to jump in the race as well, which became open after Republican Sen. Jeff Flake announced his retirement. McSally is more closely aligned with Senate Majority Leader Mitch McConnell, who listed her as a top recruit. 

Arpaio had floated challenging Flake, and said he was considering running after Flake retired. But Arpaio said multiple times in the past that he was considering running for office — and ended up not running. 

Arpaio has become a prominent figure among conservatives with hard-line stances on illegal immigration, who favor his controversial tactics.  While sheriff he set up a “Tent City” jail, which was criticized for creating cruel conditions for inmates. He also led a crackdown on illegal immigration.

Trump won the state by 4 points in 2016. Inside Elections with Nathan L. Gonzales rates the race a Tossup.