Most of the outstanding ballots are coming from Arizona's largest county, Maricopa County, which is home to Phoenix and includes Kyrsten Sinema's congressional district. | Christian Petersen/Getty Images Elections Sinema takes slim lead in too-close-to-call Arizona Senate race

Democratic Rep. Kyrsten Sinema took a narrow 9,610-vote lead over GOP Rep. Martha McSally Thursday evening as Arizona’s election authorities counted more ballots in the state’s uncalled Senate race.

The lead amounts to less than half a percentage point with more than 1.8 million votes counted. McSally was up by 17,703 votes earlier in the day, before the counties processed another 160,000 votes — but about a half-million more votes remain to be counted across Arizona, according to both campaigns.


Most of the outstanding ballots are coming from Arizona's largest county, Maricopa County, which is home to Phoenix and includes Sinema's congressional district. Sinema held a slight edge of about 1 point over McSally in the county as of Thursday afternoon, but the new votes counted Thursday expanded the Democrat’s Maricopa edge to 2.5 points. That’s the outcome Democrats had hoped for, while Republicans were expecting McSally’s tally there to improve.

The state will continue to count early votes cast before the election daily until the race is resolved.

“Arizonans must have faith that their votes are counted, and we are working diligently to ensure that count proceeds in a fair, transparent, and timely manner that voters can trust,” Andrew Piatt, Sinema’s campaign manager, said in a statement Thursday afternoon. He said he was confident Sinema would prevail once the remaining half a million votes are counted.

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"With half a million ballots left to count, we remain confident that as votes continue to come in from counties across the state, Martha McSally will be elected Arizona's next senator," McSally campaign CEO Jim Bognet said in a statement.

Arizona is one of three remaining Senate races without a declared winner. In Florida, Republican Gov. Rick Scott is ahead of Democratic Sen. Bill Nelson by two-tenths of a percentage point, but the race is headed for a recount. And in Mississippi, Republican Sen. Cindy Hyde-Smith and Democrat Mike Espy will face off in a late November special-election runoff.

Republicans have already secured 51 Senate seats to 46 for Democrats, after three Democratic incumbents and one GOP senator lost on Tuesday night.

Hyde-Smith is expected to win the Mississippi runoff. But depending on the results in Arizona and Florida, the Republican majority in the next Senate could be as small as 52 seats or as big as 54. That spread could be significant on legislation and judicial confirmations over the next two years — as well as in the 2020 elections, when Republicans must defend 22 Senate seats compared to just 12 for Democrats.

In Arizona, Sinema led comfortably in polling throughout the summer and fall, but McSally closed the gap by late October. The race was one of the most expensive in the country, with nearly $30 million spent by both parties.

Sinema and McSally are vying to replace Republican Sen. Jeff Flake, who retired after clashing with President Donald Trump.

Both campaigns are digging in for a protracted coda to the election. McSally’s campaign sent out a fundraising request Thursday evening for donations to help fund an “army of attorneys and observers” to fend off any legal challenges once the votes are tallied.

McSally’s campaign also tweeted that she was “dreading a long and painful process.” The tweet included a photo of her in a dentist’s chair.