Democrat Kyrsten Sinema flipped into the lead over Republican Martha McSally late Thursday as votes are still being counted in several counties.
McSally had held the lead early Thursday, two days after the Tuesday midterm election.
That lead flipped late Thursday with an updated batch of votes counted putting Sinema in the lead with 49.1 percent of the vote, or 932,870 votes.
Latest numbers from the Arizona Secretary of State as reported by the Arizona Republic show Maricopa County with 345,000 votes yet to be counted (150,000 early ballots, 195,000 Election Day drop-off, provisional, or out-of-precinct ballots), Pima County with 54,000 yet to be counted (36,000 early and 18,000 provisional ballots), Pinal County with 31,800 early ballots yet to be counted, and Coconino County with 10,600 votes remaining to be counted.
There are small batches of votes yet to be counted in other counties as well: Mohave County 8,000, Santa Cruz County 6,100, Yavapai County 6,100, Apache County 4,600, Navajo County 4,000, Yuma County 3,100, Cochise County 1,700, and La Paz County 580.