(CNN) Democratic US Rep. Kyrsten Sinema has pulled slightly ahead of Republican Rep. Martha McSally in the close race for US Senate in Arizona.

As of a few minutes before 8 p.m. ET Thursday, Sinema held a slim lead with 49.1% of the vote, while McSally was right behind with 48.6% of the vote, with 83% of the vote reported, CNN results show. Nearly 9,000 votes separate McSally from Sinema.

Sinema's lead comes after roughly 127,000 votes in Maricopa County -- the state's most populous county, which includes Phoenix -- were counted Thursday. Thousands of votes still remain to be counted in the state.

Individual counties in Arizona will continue to update their vote counts periodically until ballots are certified.

"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," Sinema for Arizona campaign manager Andrew Piatt said in a statement.

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