Former Maricopa County Sheriff Joe Arpaio's entry into the Arizona Senate race is splitting conservatives, according to the latest polling.
Mr. Arpaio, who announced his bid Tuesday, leaped into second place in the GOP primary race, while Rep. Martha McSally, who is expected to announce her campaign later this week, is now the leader.
Former state Sen. Kelli Ward, who had been on top before, slipped to third place, according to OH Predictive Insights, which rushed into the field with a survey after Mr. Arpaio's announcement.
The race is tight: Ms. McSally garners 31 percent of the vote, Mr. Arpaio is at 29 percent and Ms. Ward is at 25 percent, the poll found.
"Everyone knows Joe. He has near-unanimous name recognition. But it doesn't mean he is universally loved. It will be a challenge convincing voters he's a new Joe," said Mike Noble, the company's chief pollster.
In November, Ms. Ward was in the led 42-34 over Ms. McSally.
Ms. McSally's support appears to have dropped only slightly, while Mr. Arpaio has picked up a number of Ms. Ward's supporters and undecided voters.
Arizona Republicans said an endorsement from President Trump would be a huge factor in the race, should he choose to weigh in.
Former White House political adviser Stephen Bannon's backing, meanwhile, is now viewed as poisonous, the poll found. He has embraced Ms. Ward in the race.
Given a hypothetical race where Mr. Trump endorsed Mr. Arpaio, it would shoot him to the lead over Ms. McSally.