As President Trump and his campaign battle Joe Biden down to the wire in the race for the White House, they have focused their fury on an unexpected target: Fox News.

The campaign has been furious at Fox since its decision desk was the first to project Biden would win Arizona. The network made the call around 11:30 p.m. Tuesday. Only The Associated Press has joined Fox in projecting Biden to win the state.

The anger toward Fox is palpable among Trump allies. The campaign urged surrogates to call the network directly on Thursday to urge them to withdraw the call of Arizona, according to a person familiar with the matter.

Trump associates have spent the past 48 hours blasting the decision, some of them doing so on Fox's airwaves. The campaign made it personal on Thursday when it sent out a release decrying Arnon Mishkin, the head of the Fox decision desk, as a “Democrat operative” and highlighting his past donations to the Obama presidential campaign in 2008.

While Mishkin did give to Obama and other Democrats, he has also donated to Republicans, including former Rep. Bruce Poliquin (R-Maine).

Mishkin’s call of Arizona is said to have infuriated Trump on Tuesday night as it gave momentum to Biden on election night even as millions of votes were still being counted. The president's campaign has been adamant that Trump will carry Arizona, potentially as early as Friday, but Fox has stood by its call, and stood by Mishkin.

“Fox News has already called Arizona. That’s caused a lot of heartburn in the Republican Party, but I did check in with our decision desk earlier today, and they are not wavering. They say that our call in Arizona is right,” Chris Wallace said on the network Thursday.

Fox News did not issue a statement in response to the Trump campaign's attacks.

The spat with the Fox News decision desk has been one of multiple tense moments between the Trump campaign and the president’s favorite network since Election Day began. The clashes followed weeks of complaints by Trump, who regularly attacks the network’s news anchors while praising its opinion hosts like Sean Hannity and Laura Ingraham.

White House press secretary Kayleigh McEnany appeared on Fox News on Wednesday night in the role of campaign adviser to assert that the president's staff would seek to invalidate ballots counted after Election Day in Pennsylvania.

Anchor Martha MacCallum pressed McEnany on the issue, explaining that she was essentially arguing for disenfranchising voters who had legally cast ballots based on state law.

“Even if they voted on Nov. 3 in Pennsylvania because they were told that that was okay to do, you’re going to throw their — toss their ballot out if it doesn’t come in until the day after or two days after?” MacCallum asked. 

Tim Murtaugh, the campaign's communications director, went after Fox News while appearing on the network on Wednesday, accusing the decision desk of giving Biden an opening to declare himself president-elect by calling Arizona in his favor.

"I don’t think you want that hanging around your neck," Murtaugh said.

Trump has appeared on the network more than any other by far during his presidency. At one of his final rallies before Election Day, Trump did a roll call of Fox News opinion hosts he liked. As polls opened on Tuesday morning, Trump called into “Fox & Friends.”

But the president has become increasingly agitated with Fox News in the final months of the campaign, seemingly setting up the network to shoulder some blame if he loses.

The president bristled at the network's live coverage of former President Obama's campaign speeches in the final week of the race, and he has lamented multiple times that the network is not what it once was under the leadership of Roger Ailes, who resigned amid sexual harassment allegations in 2016 and died in 2017.

“The biggest difference between now and 2016 is @FoxNews,” Trump tweeted in late October. “They are a whole different deal. Despite this, our campaign is doing much better, with bigger crowds and even more (much!) enthusiasm, than we had in 2016.”

The network finds itself in a potentially uncomfortable situation as the only one to have called Arizona for Biden. The former vice president only needs to win one more state of Nevada, Pennsylvania and Georgia to reach 270 electoral votes, meaning Fox could be in a position to call the race for Biden before others.

The Associated Press has also called Arizona for Biden.

Biden was leading in Nevada as of late Thursday afternoon and quickly gaining ground on Trump in Pennsylvania, with the possibility of surpassing him by later in the evening.

Mishkin, who did multiple interviews leading up to Election Day to explain the network's approach to calling races, was adamant that final decisions would be made solely on the basis of math and data.

“Arithmetic is more important than politics when it comes to making a decision and you've just got to check your preferences at the door and decide who has won this thing,” he said on "Fox News Sunday."

Updated at 6:03 p.m.