PRESIDENT TRUMP tweeted Thursday that the presidential election results “may NEVER BE ACCURATELY DETERMINED” because of the “new and unprecedented massive amount of unsolicited ballots.” “RIGGED ELECTION in waiting,” he exclaimed in another tweet.

This is not the first time Mr. Trump has cast doubt on the legitimacy of a vote that polls indicate he is likely to lose, and it will not be the last. Rather than internalizing the notion that the coming election is likely to be fraudulent — which experts adamantly insist is not the case — Americans must take every such utterance as more evidence of the president’s underlying goal: to discredit and deny their choice, if they are to eject Mr. Trump from the White House. Typically, it doesn’t pay to be distracted by every outlandish presidential tweet. But Mr. Trump’s repeated insistence that he can lose only if there is fraud must be called out for what it is: un-American, antidemocratic hogwash.

Mr. Trump is spinning his fiction around one fact: Because of the covid-19 pandemic, more people than usual will vote by mail this year. Polls show that Democrats are more likely to do so than Republicans, so Mr. Trump might appear to be ahead in the count on election night in some key states. Then it will probably take days to count absentee ballots. The president will no doubt allege fraud as his lead diminishes or disappears.

He may be abetted by powerful Republicans who have aided his nefarious effort already. Attorney General William P. Barr has repeatedly speculated — without evidence, he admitted — that foreign governments might print up masses of fraudulent ballots. In an interview published in the Chicago Tribune last week, Mr. Barr warned of widespread “selling and buying votes.”

“Someone will say the president just won Nevada. ‘Oh, wait a minute! We just discovered 100,000 ballots! Every vote will be counted!’ Yeah, but we don’t know where these freaking votes came from,” Mr. Barr said. In the same interview in which he sought to discredit the mail-in balloting that several states use exclusively and have for years without major incident, Mr. Barr accused “liberals” of “creating an incendiary situation where there will be loss of confidence in the vote.”

“Our democracy’s enemies, foreign and domestic, want us to concede in advance that our voting systems are faulty or fraudulent,” Daniel Coats, Mr. Trump’s former director of national intelligence, wrote in a New York Times op-ed published Thursday. “No American, and certainly no American leader, should want such an outcome. Total destruction and sowing salt in the earth of American democracy is a catastrophe well beyond simple defeat and a poison for generations,” he wrote. No need to name the leader he had in mind.

Mr. Coats then endorsed an idea we proposed previously: “a supremely high-level bipartisan and nonpartisan commission to oversee the election” that would monitor voting and vote counting and “confirm for the public that the laws and regulations governing them have been scrupulously and expeditiously followed — or that violations have been exposed and dealt with.”

Congress should empanel an election commission. If it does not, senior statesmen should form one on their own. Former presidents George W. Bush and Barack Obama would be natural leaders for such a panel. And Americans should understand that there is nothing untoward if many people vote by mail — and if the result of their voting is not confirmed on election night.

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