The first on-air call came from CNN at 11:24 a.m. Saturday — former vice president Joe Biden was projected to win Pennsylvania’s 20 electoral votes, and therefore, would be the next president.

Within the following minute, NBC, CBS, MSNBC and ABC projected the same on air. The Associated Press made the call at 11:26 a.m., and Fox News announced it at 11:40 a.m.

The Washington Post made the call at 11:34 a.m. that Biden was projected to win Pennsylvania and the presidency.

Each news outlet makes its own determination on these calls, relying on “decision desks” staffed by political scientists, researchers and analysts who operate independently from newsroom political staffs. The AP and Fox News were the first major news organizations to call Arizona, which meant that for several days their counts had Biden at just six electoral votes shy of the 270 needed to win the presidency. Fox News called Arizona for Biden at 11:20 p.m. Tuesday, and the AP followed at 2:50 a.m. Wednesday.

None of the other major news organizations, which rely on the data firm Edison Research to make race calls, have projected a winner in Arizona yet because of a lack of clarity about the number and type of ballots that remain to be counted. That means that Fox and AP are touting a higher electoral vote tally for Biden than the other news organizations.

Fox’s projection that Biden would be the next president came at the same time as it called that he would win Nevada’s six electoral votes, followed by the AP about 30 minutes later. Other media organizations followed later in the day.

Fox and the AP use different data from their counterparts to make these analyses, having joined forces after the 2016 election to hire a University of Chicago-affiliated research operation. AP VoteCast, which conducts surveys online and by phone, also is used by NPR, “PBS NewsHour,” Univision, USA Today and the Wall Street Journal — all of which have called Arizona for Biden. At Fox, the data set is called Fox News Voter Analysis, and its decision desk makes the network’s calls.

The early Fox News call on Arizona drew the ire of the Trump campaign, which sent out an email missive attacking Arnon Mishkin, the management consultant who runs the network’s decision desk, by name. When asked about the campaign’s insistence that the outstanding votes left to be tabulated would be sufficient for Trump to overtake Biden’s lead in the state, Mishkin, explained why his team didn’t see a path to success for the president in Arizona, adding “if a frog had wings.”

Other news organizations had been wary of calling Arizona for Biden, where his lead is shrinking as more votes are tallied. “In Arizona, it is getting really, really close,” John Lapinski, NBC’s director of elections, said on MSNBC on Friday morning. “I know other people called that race on election night. Those were kind of crazy calls. This race could go down do to the wire, and we’re just going to have to see, and it will depend on if President Trump, you know, does as well as the earlier batches. And if that’s the day, he could win this. I think I’d rather be vice president Biden because he has a slight edge, but ever so slight.”

Meanwhile, Decision Desk HQ, another research company that calls races, projected on Friday morning that Biden won. Outlets that use Decision Desk HQ, such as Vox and Business Insider, published stories Friday calling Biden the president-elect. This meant that Maine’s Bangor Daily News, which also partners with Decision Desk HQ, was well ahead of much larger newspapers when it ran this headline on its Saturday-morning front page: “Biden projected as winner.”

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