Allan Lichtman, a professor at American University in Washington D.C., was one of the few who correctly predicted that Donald Trump would win last year’s election. And while he’s forecast a possible impeachment before, Lichtman now says it could be a mere months before Trump is out of the White House.

“The odds on a Trump impeachment or a Nixon-style resignation are now quite high,” Lichtman told the Daily Star in an interview published last week. “It will depend on what other information emerges from Robert Mueller’s investigation. It would likely come by the spring of 2018, or whenever Republicans come to believe that Trump is jeopardizing their re-elections in 2018.”

The Justice Department’s special counsel investigation, which is being led by Mueller, issued indictments last week to Paul Manafort and his associate Rick Gates. While Mueller likely cannot indict Trump, says Lichtman, he may be able to recommend impeachment.

“It matters little to the nation whether Manafort or Gates go to jail, it [matters] a great deal with the president in control of the nuclear codes is guilty of impeachable offenses, which do not have to be indictable crimes,” he said. “Precedent suggests, although it is not a settled matter, that Mueller cannot indict Trump, but he can recommend impeachment to the House or provide information that becomes the basis for impeachment.”

Lichtman, who has correctly predicted the outcomes of 30 years of presidential elections, previously foresaw a Trump victory in the 2016 election using what he refers to as a set of “keys.” However, Lichtman also immediately predicted that Trump would be impeached.

“I’m going to make another prediction — this one is not based on a system, it’s just my gut,” the professor told the Washington Post in November last year. “If Donald Trump wins, I predict the Republicans in Congress will impeach him. They don’t want Trump as president because they can’t control him.”

He added: “I’m quite certain Trump will give someone grounds for impeachment either by doing something that endangers national security because it helps his pocketbook.”