“It’s a false dichotomy to say Democrats have a choice between doing what is right and what is constitutional and what is politically right. Impeachment is also politically right,” Lichtman told CNN’s Brooke Baldwin on Wednesday.

Lichtman has developed a system of 13 “key factors” that help determine whether the party in the White House will maintain its hold, according to CNN. The factors range from whether the party has an incumbent president running to the country’s short- and long-term economic conditions to foreign policy successes and failures. If the party loses out on six factors or more, he says they will lose the presidency.

Lichtman says the Trump administration is down three key factors: Republican losses in the midterms elections, a “lack of foreign policy success” and Trump’s “limited appeal to voters,” CNN reported. Impeachment would trigger a fourth key — scandal over the proceeding’s public nature.