What did Donald Trump do today?

He invented a new rule about which ballots should count.

At a rally in North Carolina, Trump was asked about reports that he plans to declare victory prematurely on Election Night regardless of how many ballots had been counted. He denied it—and then basically confirmed it. 

For once, absentee ballots heavily favor Democrats, and those are almost always counted last. Given the staggering number of voters who voted early this year avoid exposing themselves to COVID-19, Trump will probably "win" the in-person-only vote in many critical states. In a rambling answer, Trump called it "terrible" (nine times) that the election couldn't be decided on that basis.

I think it's a terrible thing when ballots can be collected after an election. I think it's a terrible thing when people or, or states, are allowed to, uh, tabulate ballots for a long period of time after the election is over. Because it can only lead to one thing, and it's very bad. You know what that thing is. I think it's a very dangerous terrible thing. And I think it's terrible when we can't know the results of an election the night of the election in a modern-day age of computers. I think it's a terrible thing, and I happen to think it was a terrible decision for our country, made by the Supreme Court. I think it was a terrible decision for our country. And I think it's a very dangerous decision. Because you're gonna have one or two or three states, depending on how it ends up, where they're tabulating ballots, and the rest of the world is waiting to find out, and I think there's great danger to it, and I think a lot of fraud and misuse could take place. I think it's a terrible decision, by the Supreme Court. A terrible... decision. Now I don't know if that's gonna be changed, because we're gonna go in, the night of, as soon as that election's over, we're going in with our lawyers, but we don't want to have Pennsylvania, where you have a political governor, a very partisan guy, and we don't want to have other states, like Nevada, where you have the head of the, the, Democratic... clubhouse [sic], as your governor. We don't want to be in a position where he's allowed to, every day, watch ballots come in, "Gee, if we could only find ten thousand more ballots." Because we're doing great in Nevada, we're doing great in Arizona, we're doing great all over. But if you take Nevada or Pennsylvania — and everyone knows what happens in Philadelphia, you don't have to say it, but I've read about it for years, and I don't think it's fair that we have to wait a long period of time after the election. If people wanted to get their ballots in, they should have gotten their ballots in long before that, long time. They don't have to put their ballots in the same day, they could have put their ballots in a month ago. And we think it's a ridiculous decision.

In other words: Trump is saying that voters whose legal ballots were cast on time but arrive late should be thrown out, because they weren't excited enough to vote a month in advance. This matters in states like Pennsylvania—which he absolutely must win, and where Democrats are voting by mail in far greater numbers than Republicans—where ballots postmarked on or before Election day can be counted up to three days later. 

This is not how elections work.

Trump has openly admitted to sabotaging the US Postal Service's ability to deliver ballots in a timely fashion, and he's said why: because he believes that Republicans can't get elected if voters can cast their ballots by mail and have them count. 

It's worth noting that the group most likely to have their votes thrown out under Trump's "Election Day decision" rule are military ballots. Normally, those favor Republican candidates, but Trump has no particular reason to want servicemembers' votes to count either: he is astonishingly unpopular with the troops for a Republican.

Why should I care about this?

• The American people, not the incumbent president, get to decide who the next president is.

• In a democracy, you don't get to make up new rules about whose votes count 48 hours before Election Day.

• Nobody who thought he would win an election fairly would try to sabotage Americans' faith in the process like this.