So if Candidate A is winning 500,000 to 400,000 but 150,000 ballots are still outstanding then they'll make the call for Candidate A because there is no reason to think that the outstanding ballots will be that much different in distribution than the already counted ballots. This can be adjusted based on historical precedent as well, if you know that late counting precincts tend to vote in a certain way then you can make educated guesses as to when the results of that precinct will no longer make a difference. Even after adding in some extra margin for safety you can call the race.
The tricky part is when a race is really close and you have to count every ballot. This is when waiting 3-5 days for the mail to finish trickling in is going to cause cable news anchors to lose sleep.
https://www.washingtonpost.com/powerpost/six-weeks-later-ele...
What happens when the postmark is not legible? I don't read postmarks often, but a good chunk of the time I can't make out the full date.
Yeah, other people are seeing that as his strategy, too:
https://www.nytimes.com/2020/08/11/opinion/trump-election-da...
> There’s no mystery about what President Trump intends to do if he holds a lead on election night in November. He’s practically broadcasting it.
> First, he’ll claim victory. Then, having spent most of the year denouncing vote-by-mail as corrupt, fraudulent and prone to abuse, he’ll demand that authorities stop counting mail-in and absentee ballots. He’ll have teams of lawyers challenging counts and ballots across the country.
> He also seems to be counting on having the advantage of mail slowdowns, engineered by the recently installed Postmaster General Louis DeJoy. Fewer pickups and deliveries could mean more late-arriving ballots and a better shot at dismissing votes before they’re even opened, especially if the campaign has successfully sued to block states from extending deadlines. We might even see a Brooks Brothers riot or two, where well-heeled Republican operatives stage angry and voluble protests against ballot counts and recounts.
> If Trump is leading on election night, in other words, there’s a good chance he’ll try to disrupt and delegitimize the counting process. That way, if Joe Biden pulls ahead in the days (or weeks) after voting ends — if we experience a “blue shift” like the one in 2018, in which the Democratic majority in the House grew as votes came in — the president will have given himself grounds to reject the outcome as “fake news.”
> The only way to prevent this scenario, or at least, rob it of the oxygen it needs to burn, is to deliver an election night lead to Biden. This means voting in person. No, not everyone will be able to do that. But if you plan to vote against Trump and can take appropriate precautions, then some kind of hand delivery — going to the polls or bringing your mail-in ballot to a “drop box” — will be the best way to protect your vote from the president’s concerted attempt to undermine the election for his benefit.