President Donald Trump's angry insistence in the last minutes of Tuesday's debate that there was no way the presidential election could be conducted without fraud amounted to an extraordinary declaration by a sitting American president that he would try to throw any outcome into the courts, Congress or the streets if he was not re-elected.

His comments came after four years of debate about the possibility of foreign interference in the 2020 election and how to counter such disruptions. But they were a stark reminder that the most direct threat to the electoral process now comes from the president of the United States himself.

His unwillingness to say he would abide by the result and his disinformation campaign about the integrity of the American electoral system went beyond anything President Vladimir Putin could have imagined. All Putin has to do now is amplify the president's message, which the Russian leader has already begun to do.

Everything Trump said in his faceoff with Joe Biden he had already delivered in recent weeks, in tweets and rallies with his faithful. But he had never before put it all together in front of such a large audience as he did Tuesday night.

He began the debate with a declaration that balloting already underway was "a fraud and a shame" and proof of "a rigged election."

It quickly became apparent that the president was doing more than simply trying to discredit the mail-in ballots that are being used to ensure voters are not disenfranchised by a pandemic — the same way of voting that five states have used with minimal fraud for years.

He followed it by encouraging his supporters to "go into the polls" and "watch very carefully," which seemed to be code words for a campaign of voter intimidation aimed at those who brave the coronavirus risks of voting in person.

And his declaration that the Supreme Court would have to "look at the ballots" and that "we might not know for months because these ballots are going to be all over" seemed to suggest that he will try to place the election in the hands of a court where he has been rushing to cement a conservative majority with his nomination of Judge Amy Coney Barrett.

And if he cannot win there, he has already raised the possibility of using the argument of a fraudulent election to throw the decision to the House of Representatives, where he believes he has an edge, since every state delegation gets one vote in resolving an election with no clear winner. At least for now, 26 of those delegations have a majority of Republican representatives.

What is striking is how Trump's fundamental assessment that the election would be fraudulent differs so sharply from that of some of the officials he has appointed.

Trump himself has provided no evidence to back up his assertions, apart from citing a handful of Pennsylvania ballots discarded in a dumpster — and immediately tracked down and counted by election officials.

Taken together, his attacks on the integrity of the coming election suggested that a country that has successfully run presidential elections since 1788 (a messy first experiment, which stretched just under a month) through civil wars, world wars and natural disasters now faces the gravest challenge in its history to the way it chooses a leader and peacefully transfers power.

"We have never heard a president deliberately cast doubt on an election's integrity this way a month before it happened," said Michael Beschloss, the presidential historian and author of "Presidents of War." "This is the kind of thing we have preached to other countries that they should not do. It reeks of autocracy, not democracy."