(NewsNation) — Election Day may have wrapped up on Tuesday, but some of the races remain close in some states, and that makes every outstanding ballot critical to the final outcomes.

Such is the case in Arizona, as reports estimate there were over half a million ballots still to be opened statewide as of Friday.

In Maricopa County alone, election officials reported Friday afternoon there were some 350,000 uncounted ballots, and they expect to tabulate somewhere around 60,000-70,000 ballots each night.

A batch of some 70,000 votes released Friday night from Maricopa County increased incumbent Sen. Mark Kelly’s lead over Republican Blake Masters. As a result, Decision Desk HQ projected Kelly the winner.

The tranche being processed consist of mail-in ballots and early ballots dropped off on Election DAy, which take an especially long time in Arizona due to how the state’s laws are set up. It’s a process that requires each ballot to be opened, sorted and signature-verified by bipartisan teams.

Arizona’s gubernatorial race between Secretary of State Katie Hobbs and former television news anchor Kari Lake, remained uncalled as of Friday night, with Hobbs holding a roughly 1-point lead.

Maricopa County officials have attributed the long counting times to the sheer number of ballots that are left. Voters dropped off 290,000 ballots on Election Day, smashing the previous Maricopa County record by 70%.

Many polling experts believe that is the most important number to pay attention to in assessing where and when the governor’s race will be likely decided.

In a statement Friday night, the Republican National Committee criticized Maricopa County’s counting process, saying the election has “exposed deep flaws” in it.

“Arizona deserves better — transparency, certainty, efficiently — and most importantly, an accurate and prompt announcement of election results that can be accepted by all voters,” the RNC said.

It demanded the county institute around-the-clock shifts to finish the count and threatened legal action.