Helmut Norpoth, a Stony Brook University professor of political science named who developed an almost perfect statistical formula model that predicts who will become president, has declared that if Donald Trump wins the Republican nomination, he will almost certainly become President of the United States.

The system utilizes the performance of a candidate within their own political party along with “patterns in the electoral cycle” to predict its winner. According to the school’s newspaper, the latter factor “studies a pattern of voting in the presidential election that makes it less likely for an incumbent party to hold the presidency after two terms in office.” That portion of the formula doesn’t take into account who each party nominates or the condition of the country at the time.

At first, as he told the university paper, Norpoth wanted to see what the political picture would look like if Trump were to face Sanders in the election. “When I started out with this kind of display a few months ago, I thought it was sort of a joke.” he said. “Well, I’ll tell you right now, it ain’t a joke anymore.”

The model, which has correctly identified and predicted the winner of every election but one since 1912—the one miss was the 1960 winner John F. Kennedy—has surmised that if the ballot comes down to Democratic frontrunner Hillary Clinton and Trump in the upcoming November election, the latter has a 97 percent chance of entering the White House. If Bernie Sanders wins the democratic nomination, the odds of Trump winning leap up to 99 percent.

More: Statistician with Near-Perfect Formula Says Trump Will Win If He Gets Nomination