Donald Trump is in trouble, according to a model that has correctly predicted the winner of every presidential race since Ronald Reagan in 1980.

This time around the model — run by Moody’s Analytics — says a Democrat will win the White House. Hillary Clinton is widely expected to be the Democratic nominee.

It’s a bad sign for Trump. Moody’s has been predicting a Democratic triumph since last August, but the margin of victory is getting bigger for the left as the economy has stayed relatively strong and President Obama’s approval rating has risen.

The reason a Democrat will win isn’t about polling or personalities, it’s about economics, says Moody’s. The economy is the top issue in just about every election. When the economy is doing well, the party currently in office usually wins again. When the economy is tanking, Americans vote for change.

So far, the U.S. economy is chugging along. It’s growing. Millions of people are getting jobs, home prices are rising and gas is cheap. All of this favors Democrats.