A superior court judge has denied the Arizona Republican party's request to immediately stop counting ballots in the slow-motion tally of Arizona's nail-bitter of a Senate race, but she did set up a hearing for Friday.

Maricopa County Judge Margaret Mahoney set a hearing for 2 p.m. Friday after the GOP challenged the way the county is handling mail-in ballots pending signature verifications.

In a press conference Thursday, Maricopa County Recorder Adrian Fontes said he will "follow the law" and continue to verify signatures on mail-in ballots to count votes in the 2018 midterm elections.

County officials were still counting more than 600,000 ballots, in a race where more than 2 million people cast ballots, when four local Republican parties filed the lawsuit Wednesday night. It challenges the way counties have allowed voters to fix problems with signatures on mailed-in early ballots.

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The complaint singles out the state's two biggest urban counties, which are the base of Democratic Rep. Kyrsten Sinema's support. She and Republican Rep. Martha McSally are separated by only a few thousand votes. Counting the outstanding votes could take several days.

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About three-quarters of Arizona voters cast ballots by mail. But many ballots known as "late earlies" arrive in the mail on Election Day, in the few days leading up to it or are hand delivered by the voters themselves. Those ballots can create logjams at the state's 15 county recorders' offices where vote counting is conducted.

All mailed ballots and the ballots that could have been mailed but were dropped off by the voters require a series of labor-intensive verifications. Voter signatures on the envelopes containing the ballots must be verified before the votes are tabulated.

The lawsuit asks a judge to prevent the county officials from counting certain ballots that were delivered with signature issues. It's unclear how many of those ballots exist.

Maricopa County Recorder Adrian Fontes tweeted Wednesday saying "bring it."