A professor who has accurately predicted the victor of every White House race since 1984 is not budging from his bet that Donald Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE will win this year.

“By the narrowest of possible margins, the keys still point to a Trump victory,” Allan J. Lichtman, professor of history at American University, told The Washington Post in an interview published Friday.

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Lichtman told the newspaper his system revolves around a set of 13 true or false statements about the party currently holding the White House.

The scholar said if six or more statements are false, the incumbent party loses the presidency come Election Day.

“Early on, the keys were inconclusive,” Lichtman said of the 2016 race. "And since that time, that sixth key has turned against the Democrats."

The decisive factor, he says, is the strength of third-party candidates. Libertarian presidential nominee Gary Johnson Gary Earl JohnsonWhat the numbers say about Trump's chances at reelection Presidential race tightens in Minnesota as Trump plows resources into state The Hill's Campaign Report: Biden condemns violence, blames Trump for fomenting it l Bitter Mass. primaries reach the end l Super PAC spending set to explode MORE could siphon off 5 percent or more of the popular vote, based on current polling.

“That’s a big sign of discontent with the party holding the White House. And so, again on the knife edge, you had exactly six fatal keys against the incumbent Democrats.”

Also counting against Democrats in Lichtman's system: President Obama not being able to run as an incumbent, Republicans' 2014 midterm success, the lack of a large foreign policy or military success in Obama's second term and Democratic nominee Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE's lack of charisma and national hero status.

Lichtman, who predicted Trump's victory in a separate interview last month, added his system currently foretells the Republican nominee winning the presidency, but that could change depending on two factors.

“[Johnson] could slip below that, which would shift the prediction,” he said of the Libertarian’s polling numbers, which would remove a "key" against the Democrats.

“The second qualification is Donald Trump. We have never seen anyone who is broadly regarded as a history-shattering, precedent-making, dangerous candidate who could change the patterns of history that have prevailed since the election of [former President] Abraham Lincoln in 1860."

Recent polls at both the national and state levels show a tightening race between Clinton and Trump less than two weeks from Election Day, though Clinton maintains a lead in most battlegrounds.