Kari Lake says she is gathering lawyers and gathering evidence from voters who have had trouble voting, as she refuses to concede the race for Arizona governor.
The Republican nominee said she was considering her next move after the race was called for her Democratic opponent, Katie Hobbs.
In a two-and-a-half-minute video, Ms. Lake gave no indication that she would be throwing in the towel.
Before the election, she had refused to say whether she would concede in case of defeat.
Ms Lake said: “Rest assured, I have assembled the best and brightest legal team and we are exploring every avenue to right the many wrongs that have been done in the past week.
“I am doing everything in my power to right these wrongs.”
The staunch Trump supporter pointed to long lines at some polling stations that were exacerbated by problems with ballot printers in about a third of polling stations in Maricopa County, Arizona’s largest county.
He said the issues disenfranchised voters who could not wait to cast, adding, “What happened to Arizonans on Election Day is inexcusable.”
County election officials said all ballots were counted and voters can go to any polling place in the county, many of which have little or no queues, with wait times posted online.
Election officials traced the problems to a printer setting that sometimes resulted in ballots being printed too lightly for on-site tabulators to read.
They said they used the same settings in the August primary and for pre-election testing and there were no widespread problems.
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Approximately 17,000 ballots were not scanned at the district’s polling booths and were instead placed in a drop box to be counted by more sophisticated machines at the county polling station, which became known as “box three”.
Bill Gates, the Republican chairman of the Maricopa County Board of Supervisors, accused Republican state chair Kelli Ward and other prominent Republicans of causing delays and long lines because they told their supporters not to use box three.
“This team, we’ve accepted our responsibility in this,” Gates said on Monday.
“But I’m not willing to accept responsibility for problems caused by others. And it’s clear to me that those lines were longer because leaders of a political party were spreading disinformation.”
The Republicans asked a judge to extend polling hours because of the problems, but the judge refused, saying they did not present evidence that anyone had been disenfranchised.
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Democrats voted overwhelmingly via mail-in ballots with in-person ballots on Election Day heavily favoring Republicans, because Ms. Lake and other party members had said it was safer.
Ms Lake has said little since many news outlets called the race for Ms Hobbs on Monday. Late Wednesday evening, she released a video clip of the campaign trail set to Tom Petty’s song “I Wo n’t Back Down.”
Her video on Thursday said Ms Hobbs, who is currently secretary of state, would have to withdraw from any role in the election.
The secretary of state creates the election procedures and certifies the equipment, but his office does not count the ballots.
