Arizona voting officials swat down right-wing claims of criminality in machine problems
Kari Lake / Gage Skidmore.

Officials in an Arizona county at the center of unsubstantiated right-wing claims of fraud during the US midterm election said Wednesday there was no criminality involved in isolated problems with voting machines.

Accusations of rigging mushroomed on social media platforms and were amplified by former president Donald Trump after Maricopa County reported a minority of tabulation machines were not working during Tuesday's vote.

"With regard to comments like 'criminal' or 'rigged,' there's absolutely no basis for that statement," Bill Gates, Chairman of the Maricopa County Board of Supervisors, told reporters.

The county, which includes the city of Phoenix, was under intense scrutiny because of unfounded claims of ballot-stuffing in the 2020 presidential vote, which saw Trump swept from power.

Trump's supporters, including the Republican candidate for state governor, Kari Lake, insist -- without evidence -- that Joe Biden's 10,000 vote majority there must have been the result of criminality.

Multiple inquiries have turned up no proof of wrongdoing.

Tallies show Lake narrowly trailing the Democratic incumbent, with around two-thirds of votes counted.

Around 60 of the 223 voting stations experienced difficulties on Tuesday, with machines unable to read or print ballots in some cases.

Gates reiterated his apology for the incidents, which caused long lines at some polling places in Phoenix and its suburbs, but said no one was prevented from voting.

Affected voters were able to deposit their ballots in secure boxes for counting at the central elections center, or to go to a polling station where the machines were working.

Gates said around seven percent of in-person votes, or 17,000, were affected.

The vast majority of votes in Maricopa County were cast early, often by mail.

As of Wednesday morning, county officials had tallied almost 1.2 million votes, Gates said.

Around 400,000 votes are yet to be counted, with workers expected to have nearly all processed by Friday.

"We understand that the people of Arizona are very anxious to get the results but again, pursuant to state law... it's going to take a while and again today we're asking for their patience," Gates said.