An American University professor who accurately predicted the Electoral College winners in the last nine presidential elections spoke to CNN about President Trump’s chances of being re-elected in the 2020 election. While Allan Lichtman said it’s still too early to make a final call, he believes Trump will be re-elected unless six of 13 factors happen.

"Trump wins again in 2020 unless six of 13 key factors turn against him,” the history professor told CNN. “I have no final verdict yet because much could change during the next year. Currently, the President is down only three keys: Republican losses in the midterm elections, the lack of a foreign policy success, and the president's limited appeal to voters."

Lichtman's prediction system is based on 13 true/false statements about the party that holds the White House. If six or more of the statement are false, the incumbent loses. If less than six are false, the incumbent wins. Simple! Here are Lichtman's 13 criteria -- via his book "Predicting the Next President: The Keys to the White House 2016" and as summarized by WaPo's Peter Stevenson: 1. Party Mandate: After the midterm elections, the incumbent party holds more seats in the US House of Representatives than after the previous midterm elections. 2 Contest: There is no serious contest for the incumbent party nomination. 3. Incumbency: The incumbent party candidate is the sitting president. 4. Third party: There is no significant third party or independent campaign. 5. Short-term economy: The economy is not in recession during the election campaign. 6. Long-term economy: Real per capita economic growth during the term equals or exceeds mean growth during the previous two terms. 7. Policy change: The incumbent administration effects major changes in national policy. 8. Social unrest: There is no sustained social unrest during the term. 9. Scandal: The incumbent administration is untainted by major scandal. 10. Foreign/military failure: The incumbent administration suffers no major failure in foreign or military affairs. 11. Foreign/military success: The incumbent administration achieves a major success in foreign or military affairs. 12. Incumbent charisma: The incumbent party candidate is charismatic or a national hero. 13. Challenger charisma: The challenging party candidate is not charismatic or a national hero. (CNN)

While the mainstream thinking has been that if Democrats pursue impeachment it will hurt the party and help Trump, Lichtman actually believes it may be the Left’s only chance.

"Democrats are fundamentally wrong about the politics of impeachment and their prospects for victory in 2020,” he said. “An impeachment and subsequent trial would cost the president a crucial fourth key -- the scandal key -- just as it cost Democrats that key in 2000. The indictment and trial would also expose him to dropping another key by encouraging a serious challenge to his re-nomination. Other potential negative keys include the emergence of a charismatic Democratic challenger, a significant third-party challenge, a foreign policy disaster, or an election-year recession. Without impeachment, however, Democratic prospects are grim."