Congresswoman Kyrsten Sinema, the Democratic nominee for Arizona's open Senate seat, took the lead on Thursday evening.

After a Democrat took the lead in the Arizona Senate race, President Trump joined local Republicans by raising the specter of voter fraud to argue that the election may be illegitimate.

On Thursday evening, new results from Maricopa County and Pima County pushed Kyrsten Sinema ahead over Republican Martha McSally in the neck-and-neck Arizona race to succeed Jeff Flake. Sinema currently has just 8,936 more votes than McSally.

Republican legislators and party officials in Arizona have floated the idea that Democrats are meddling in the election process. Trump, a frequent proponent of voter-fraud conspiracies, joined them on Friday, claiming that "electoral corruption" was taking place in Arizona, possibly requiring a new election.

Just out — in Arizona, SIGNATURES DON’T MATCH. Electoral corruption - Call for a new Election? We must protect our Democracy! — Donald J. Trump (@realDonaldTrump) November 9, 2018

Meanwhile, Arizona Republican Party county officials are suing to block several recorders from continuing to verify signatures on early ballots after polls have closed.

Approximately 456,000 ballots are still outstanding, according to an estimate from the Arizona Secretary of State's Office – including 345,000 ballots in Maricopa County alone. The Democratic candidate running for Superintendent of Public Instruction also took the lead on Thursday evening, and the races for Secretary of State and the Corporation Commission tightened.

On Friday, Trump told reporters that "in Arizona, all of a sudden, out of the wilderness, they found a lot of votes," giving Sinema the lead. His 2020 re-election campaign manager, Brad Parscale, took to Twitter with the explosive claim that Arizona Democrats were tampering with the outcome of an election.

"These democrat [sic] counties in Florida and Arizona are playing tricks because they just can’t accept the fact they lost. I will not be shocked if investigations lead to rampant fraud," Parscale wrote on Thursday. "Republicans need to send every lawyer we have to protect the legitimacy of these elections."

Trump has repeatedly propagated conspiracy theories regarding voting, including the false claim that millions of people cast ballots illegally in the 2016 election. He also took to Twitter on Friday to criticize possible recounts in the Florida gubernatorial and Senate races, after results showed Democrats trailing their Republican opponents by very slim margins.

One of the local elected officials feeding into the rumor was Arizona State Senator Sonny Borrelli, a Republican from Lake Havasu City who represents northwest Arizona in Legislative District 5.

I wonder also. Seems like the only Democrat controlled County precincts a problem being counted. https://t.co/K3uGQKk5em — Sonny Borrelli (@SonnyBorrelli) November 9, 2018

In an interview on Friday, Borrelli said that he finds it "extremely suspicious" that counties with a greater degree of Democratic control, such as Maricopa and Pima counties, are taking a longer time to count their ballots.

"They’re gonna find ballots?" Borrelli said. "There seems to be a chain-of-custody problem that’s in question here."

When asked if he has clear evidence for voter fraud, Borrelli said, "You’re the investigative reporter, why don’t you investigate?"

Does he think Democrats are trying to rig the election for Kyrsten Sinema?

"It’s suspicious," Borrelli said, adding, "Is there a possibility? There’s always that possibility. Look at the common denominator," referring to the counties where votes have yet to be counted.

This week, Borrelli was chosen to serve as the Republican State Senate majority whip. He said his colleagues may be considering fine-tuning election law and "tightening some stuff" during the next legislative session.

Echoing the pattern of criticism, State Representative Michelle Ugenti-Rita, a Republican, asked to examine the vote-counting procedures in Maricopa County under County Recorder Adrian Fontes, reportedly based on concerns from her constituents.

"When can I come down and view what's going on?" she wrote on Twitter. Fontes, a Democrat, was elected in 2016.

Based on the concerns I’m hearing from my constituents, I would like to see for myself what the ballot counting process looks like. Part of a healthy election process is transparency. When can I come down and view what’s going on? https://t.co/jnB8BpZ1lZ — Michelle Ugenti-Rita (@MichelleUgenti) November 9, 2018

Ugenti-Rita did not immediately return a request for comment.

At the same time, the legal effort by the Arizona GOP escalated when Republican Party chairman Jonathan Lines released a statement on Friday accusing Fontes of "deliberate, premeditated destruction of evidence" by mixing disputed and undisputed ballots.

"Such a man cannot be trusted to administer elections in Arizona," Lines said in the statement. "We are reviewing all legal options at this time and will continue to protect the rights of every legal voter in Arizona."

In the ongoing court fight, Fontes and other recorders have argued that they are following established law and procedure by continuing the signature-verification process several days after polls close. As part of that process, county officials call or write to voters to verify that the same individual actually signed the ballot if the signature doesn't appear to match the one on file.

On Thursday, Fontes called the lawsuit "an attempt to keep me from counting certain ballots."

"I'm not going to stand for that kind of denial of our voters," Fontes told reporters. "I will follow the law."

Maricopa County Superior Court Judge Margaret Mahoney initially ruled in favor of county recorders on Thursday to say they can continue the same procedure, but another hearing before Mahoney was scheduled to take place today at 2 p.m.

In a statement on Friday morning, Sinema's campaign said that the election is trending in her direction as more results come in from across the state.

“Yesterday and this morning confirmed our expectation that as the ballots are counted, Kyrsten will steadily build her advantage," campaign manager Andrew Piatt said.

More pushback to the voter-fraud line of attack came from Amy Chan, a Republican member of the Arizona Citizens Clean Elections Commission, who said that lobbing a voter-fraud accusation is irresponsible because it can demoralize voters.

"I think the counties are excellent election administrators. They always follow the law. They do the absolute best they can," Chan told Phoenix New Times.

As state election director between 2009 and 2013, Chan said her office tried to chase down claims of voter fraud, which were almost always unfounded except in the case of a tiny, single-digit number of instances – mostly "snowbirds who were registered in two places," she said.

Any ballots that are ineligible are discounted, she said, but people must realize that results can change in a close race.

"I feel like the average person out there probably understands that as ballots continue to be counted, results can change. That’s the whole point," she said.

In contrast, Chan said that there seems to be a partisan division to the voter-fraud claims, with the outcry coming entirely from Republicans. The fever at the end of an election may be having an effect, she speculated.

Chan said, "It’s often the case that when people begin to see themselves on the losing side of an election, their faith is shaken because they don’t understand why they’re not winning."