PHOENIX (AP) -- Former Arizona Sheriff Joe Arpaio's announcement that he'll run for the Senate seat being vacated by fellow Republican Jeff Flake potentially pits two conservative, pro-Donald Trump candidates against each other and could create an opening for a more moderate GOP contender to take the seat.
Arpaio made the announcement Tuesday, injecting new uncertainty and attention into the race that's already among the year's most-watched.
If Arpaio follows through and files his candidacy papers, the race could feature one of President Trump's most vocal supporters trying to replace one of his fiercest detractors. Flake has constantly criticized the president.
Until now, the Republican front-runner in the race has largely been considered to be Kelli Ward, a former state senator. Arpaio's entry could hurt her chances.
"I think he would just suck up most of her support. He is a much more prominent and visible person, he's been around so long," said David Berman, a senior research fellow at Arizona State University's Morrison Institute of Public Policy. "Most people who like Trump generally gravitate toward Arpaio."
A Senate campaign by the 85-year-old Arpaio also might aid a more moderate Republican by splitting the vote.
One possibility is U.S. Rep. Martha McSally, who colleagues say is planning a Senate run but has not yet made an announcement.
McSally has courted Trump's support in recent months while still presenting herself as middle-of-the-road. She is also seen as a strong GOP contender for the Senate seat in a possible run against Democratic U.S. Rep. Kyrsten Sinema, who represents Arizona's 9th District and has also positioned herself as a moderate candidate.
Zachery Henry, a Ward spokesman, said members of the campaign don't believe Arpaio would split the GOP vote to the detriment of Ward.
Ward, who lost a 2016 GOP primary to Sen. John McCain, has been endorsed by former Trump strategist Steve Bannon in her campaign to replace Flake.
However, she removed Bannon's name from her list of endorsements after Trump split with Bannon over comments in a newly published book critical of the president.
Trump posted a favorable tweet about Ward, after she visited his Mar-a-Lago, Florida, resort around Christmas, but he has not formally backed her.
Asked Tuesday whether the White House would support Arpaio's candidacy, spokeswoman Sarah Huckabee Sanders declined to comment.
Arpaio's announcement caused some people to wonder if he is serious about a Senate bid or simply seeking publicity. He flirted with running for governor no fewer than five times over the years before finally abandoning the idea.
The former lawman said supporters urged him to seek public office again despite his crushing 2016 defeat following six terms as sheriff of the metro Phoenix area.
Last year, he was convicted of criminal contempt of court for intentionally disobeying a 2011 court order to stop his signature immigration raids. He was spared a possible jail sentence over the summer when Trump pardoned him for disobeying a judge.
For decades, Arpaio was also known for jailing inmates in outdoor tents during Arizona's triple-digit summer heat and forcing them to wear pink underwear. His office also failed to adequately investigate more than 400 sex-crime complaints.
Arpaio's re-election defeat came amid a crush of criticism over $141 million in legal costs that Maricopa County taxpayers paid to defend him in lawsuits over his contentious immigration policies, deaths of inmates in his jails and a child sex abuse case botched by his agency.
The former sheriff said he would accept a Trump endorsement but wouldn't seek it. He also said Trump had not asked him to run for the Senate.
"If I go to my grave, I don't think I'd be happy if I didn't take the shot to run," Arpaio said.
"As time went on, I saw what was happening in D.C. — nothing is changing with the Senate," he said. "A lot of them go after the president."