President Trump’s declaration, at a 2 a.m. press conference, that he has won the election and would move in court to prevent a “fraud” in late-counted mail-in ballots certainly sets up a historic drama. His statement followed Vice President Biden’s earlier appearance, at which the Democrat declared he believes he is on track to win the election, adding: “It ain’t over until every vote is counted.”

This strikes us as a moment to stay calm and take a careful look at the numbers and to stick to the law. As we write, the big news agencies are reckoning that Mr. Biden has between 220 and 227 electoral votes. Mr. Trump is at 213. The race now hangs largely on five states — Michigan, Wisconsin, Pennsylvania, North Carolina, and Georgia. As Messrs. Biden and Trump spoke, the President was leading in all of them save Wisconsin, which is exceptionally close.

In the Badger State, when we last checked, an estimated 89% of the vote was in and showing Mr. Biden ahead by 49.3% to 49%. In Michigan, with an estimated 67% of the vote in, Mr. Trump was ahead 53.1% to 45.1%. In Pennsylvania, with 74% of the vote in, Mr. Trump led 55.6% to 43%. In North Carolina, Mr. Trump led by 50.1% to 48.6%, with 95% of the vote in. In Georgia, with 91% of the vote in, he led by 50.6% to 48.1%.

That means that Mr. Trump must hold on to all four of the states in which he currently leads. That explains his willingness to challenge the absentee ballot counting in court. In two cases last week, involving Pennsylvania and North Carolina, the Supreme Court handed at least a temporary victory to the Democrats. In Pennsylvania, it declined to step into the fray before the election, leaving officials free to count mail-in ballots for several days after election day. In the North Carolina case, it okayed receiving such ballots nine days after election day.

There were indications, though, that the rulings — in which the justices didn’t issue explanatory opinions — mightn’t mean they are done with the matter. There were at least three dissenters, with Justice Alito pointedly keeping open the possibility that the justices might return to the question. It may be that in the coming hours and days the votes will tally in a way that makes a court fight unnecessary.

In Pennsylvania, after all, Mr. Trump was, as we write, ahead by 677,988 votes. On the one hand, that is not anything like the close margins in, say, Florida’s battle for the hanging chads, where the race was decided by a few hundred votes. On the other hand, in Pennsylvania, according to the Times, requests for absentee ballots totaled more than 3 million, some 63% of which were requested by Democrats.

If all this turns into an electoral donnybrook, it won’t be for lack of a warning. Mr. Trump has for weeks been decrying the danger that the distribution of huge numbers of absentee ballots was an invitation to fraud. The Democratic press has been warning that Mr. Trump would try to suppress absentee votes. What the Supreme Court might do, we don’t know. It would not surprise us, though, if it were reading up on Bush v. Gore.

That case, in Florida, is the last time the Court decided a presidential election. The question then was in respect of a recount, not the late counting of absentee ballots. In Florida, the Nine stopped recounts for a lack of uniform methods of counting and also because Florida was running out of time. Such questions could yet erupt in court if the count doesn’t clarify in the cold light of dawn.