Democrats have padded their narrow leads in key Arizona contests, but the races for U.S. Senate and governor are still too early to call.
About a fifth of the total ballots are left to be counted.
Democratic Sen. Mark Kelly led Republican Blake Masters by 5.6 percentage points late Thursday, while Democrat Katie Hobbs was 1.4 points ahead of Republican Kari Lake in the governor's race.
Election officials in populous Maricopa County expected to begin reporting results Friday from nearly 300,000 mail ballots that were returned on Election Day.
That crucial group of ballots will provide clues about how the remaining votes will fall.