PHOENIX — KTAR political analyst Dr. Mike O’Neil told KTAR News 92.3 FM’s Mac & Gaydos on Thursday he was “90 percent” certain Democrat Kyrsten Sinema would defeat Republican Martha McSally for Arizona’s U.S. Senate seat.

Sinema took around a 9,000 vote lead over McSally in the contentious, drawn-out race after Maricopa and Pima counties released their latest totals at around 5 p.m.

O’Neil said bumps from both counties gave him confidence Sinema would become the state’s first female U.S. senator.

McSally entered the day with a lead of around 17,000 votes in the race to replace Republican Sen. Jeff Flake, who did not seek re-election.

“At this point, I know who has won this election,” O’Neil said. “Kyrsten Sinema.”

Sinema’s lead in the state’s largest county jumped from just over 8,000 to more than 27,000.

The Maricopa County Recorder’s Office said it still had about 345,000 ballots left to count and would report its next batch at 5 p.m. Friday.

About 195,000 of them are early, provisional and out-of-precinct ballots that voters submitted on Election Day. The rest are early ballots that received before the election that hadn’t yet been tabulated.

O’Neil said that provisional and late votes typically favor Democrats, which would only help Sinema.

“If (Sinema) made up that much ground in Maricopa County, where she was previously at a dead heat for all intents and purposes, there’s a big chunk of votes in Pima County that’s going to give her a big bump,” O’Neil said.

“I don’t see how she loses this election unless for some screwy reason the votes that came in for Maricopa County were some sort of selection of just Democratic enclaves and I don’t know any reason why that would be the case.”

The counting continues while a lawsuit over Tuesday’s election was playing out.

Republicans filed a lawsuit Wednesday night to challenge the way some Arizona counties count mail-in ballots.

About 75 percent of Arizona voters cast ballots by mail, but those ballots have to go through the laborious signature confirmation process, and only then can be opened and tabulated. If county recorders have issues verifying signatures they are allowed to ask voters to verify their identity.

The suit filed by four county Republican parties — Maricopa, Apache, Navajo and Yuma counties — alleges that the state’s 15 county recorders don’t follow a uniform standard for allowing voters to adjust problems with their mail-in ballots, and that two counties improperly allow those fixes after Election Day.

Even so, O’Neil is confident Sinema will win.

“If I’m wrong, it’ll be the first election I’ve miscalled in my life,” he said.

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