Few experts predicted Donald Trump would be the 45th president of the United States. One professor who did says Trump's administration won't last long.

As early as September, American University professor Allan Lichtman told The Washington Post that Trump would triumph. Now he's saying Congress will likely impeach President Trump and remove him from office before the end of his first term.

"They don't want Trump as president, because they can't control him. He's unpredictable. They'd love to have Pence — an absolutely down-the-line, conservative, controllable Republican. I'm quite certain Trump will give someone grounds for impeachment," Lichtman told the Washington Post.

Lots of Republicans said they were uncomfortable with Trump as their nominee for president. Having Mike Pence in the White House would put a more trusted establishment Republican in the job.

See the president-elect during a meeting with President Obama:



11 PHOTOS Barack Obama and Donald Trump meet See Gallery Barack Obama and Donald Trump meet U.S. President Barack Obama meets with President-elect Donald Trump (L) in the Oval Office of the White House in Washington November 10, 2016.REUTERS/Kevin Lamarque U.S. President Barack Obama (R) meets with President-elect Donald Trump to discuss transition plans in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque U.S. President Barack Obama meets with President-elect Donald Trump (L) in the Oval Office of the White House in Washington November 10, 2016.REUTERS/Kevin Lamarque U.S. President Barack Obama (R) meets with President-elect Donald Trump to discuss transition plans in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque U.S. President Barack Obama meets with President-elect Donald Trump (L) in the Oval Office of the White House in Washington November 10, 2016.REUTERS/Kevin Lamarque U.S. President Barack Obama meets with President-elect Donald Trump to discuss transition plans in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque U.S. President Barack Obama (R) greets President-elect Donald Trump in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque U.S. President Barack Obama meets with President-elect Donald Trump (L) to discuss transition plans in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque U.S. President Barack Obama shakes hands with President-elect Donald Trump (L) to discuss transition plans in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque TPX IMAGES OF THE DAY U.S. President Barack Obama (R) greets President-elect Donald Trump in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque U.S. President Barack Obama shakes hands with President-elect Donald Trump (L) to discuss transition plans in the White House Oval Office in Washington, U.S., November 10, 2016. REUTERS/Kevin Lamarque Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

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It's worth noting that Lichtman's prediction that Trump would win was based on his own system that's been right in all but one presidential election since 1984. It wasn't correct in 2000, when Al Gore won the popular vote but not the Electoral College. But Lichtman's belief that Trump will get impeached is just a gut feeling.

This is all contingent on Trump actually committing a crime.

Trump is already facing some legal troubles in civil court. He's due to testify in one of the Trump University cases in late November.

The Constitution doesn't specify that the impeachable offense has to happen while the person is president, but political science professor Eric Schickler said, "The conventional understanding of impeachment is that it is due to actions taken while in office."

See how media around the world responded to Trump's win:



14 PHOTOS Newspapers around the world react to Trump's win See Gallery Newspapers around the world react to Trump's win A businessman walks past copies of the London Evening Standard newspaper, featuring a picture of U.S. President-elect Donald Trump on its front page, waiting to be picked up in the square mile financial district of the City of London, U.K., on Wednesday, Nov. 9, 2016. Donald Trump was elected the 45th president of the United States in a stunning repudiation of the political establishment that jolted financial markets and likely will reorder the nation's priorities and fundamentally alter America's relationship with the world. Photographer: Chris Ratcliffe/Bloomberg via Getty Images A Mexican holds a newspaper with headlines referring to the eventual triumph of Donald Trump on November 9, 2016 in Mexico City. / AFP / PEDRO PARDO (Photo credit should read PEDRO PARDO/AFP/Getty Images) Mexican newspapers with their front page referring to the eventual triumph of US presidential candidate Donald Trump on November 9, 2016 in Mexico City. / AFP / YURI CORTEZ (Photo credit should read YURI CORTEZ/AFP/Getty Images) A Mexican holds a newspaper with headlines about on the eventual triumph of Donald Trump on November 9, 2016 in Mexico City. / AFP / PEDRO PARDO (Photo credit should read PEDRO PARDO/AFP/Getty Images) Copies of a special edition of the Financial Times newspaper, featuring a picture of U.S. President-elect Donald Trump on its front page, sit waiting to be picked up in the square mile financial district of the City of London, U.K., on Wednesday, Nov. 9, 2016. Donald Trump was elected the 45th president of the United States in a stunning repudiation of the political establishment that jolted financial markets and likely will reorder the nation's priorities and fundamentally alter America's relationship with the world. Photographer: Chris Ratcliffe/Bloomberg via Getty Images A Mexican newspaper with its front page referring to the eventual triumph of US presidential candidate Donald Trump on November 9, 2016 in Mexico City. / AFP / YURI CORTEZ (Photo credit should read YURI CORTEZ/AFP/Getty Images) A Mexican newspaper with its front page referring to the eventual triumph of US presidential candidate Donald Trump on November 9, 2016 in Mexico City. / AFP / YURI CORTEZ (Photo credit should read YURI CORTEZ/AFP/Getty Images) A Mexican reads a newspaper with headlines about on the eventual triumph of Donald Trump on November 9, 2016 in Mexico City. / AFP / PEDRO PARDO (Photo credit should read PEDRO PARDO/AFP/Getty Images) View of Guatemalan newspapers informing about the victory of US presidential candidate Donald Trump in their front pages, in Guatemala City on November 9, 2016. / AFP / JOHAN ORDONEZ (Photo credit should read JOHAN ORDONEZ/AFP/Getty Images) Colombian newspapers report the victory of US presidential candidate Donald Trump on their front pages, in Medellin, Colombia, on November 9, 2016 / AFP / STR / RAUL ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images) An 'I Voted' sticker adorns a newspaper at an election watch party organized by the American Chamber of Commerce in Hong Kong, China, on Wednesday, Nov. 9, 2016. Republican Donald Trump was projected to win North Carolina and Florida, an unexpectedly strong showing in results Tuesday night that potentially throws the balance in the presidential race to Michigan and Wisconsin, key parts of Hillary Clinton's Midwestern electoral firewall. Photographer: Anthony Kwan/Bloomberg via Getty Images TOKYO, JAPAN - NOVEMBER 09: A man distributes an extra edition of a newspaper featuring a front page report on the U.S. Presidential Election and Republican President-elect Donald Trump on November 9, 2016 in Tokyo, Japan. Donald Trump defeated Democratic presidential nominee Hillary Clinton to become the 45th president of the United States. (Photo by Yuya Shino/Getty Images) Chilean newspapers report the victory of US presidential candidate Donald Trump on their front pages, in Santiago, on November 9, 2016 / AFP / MARTiN BERNETTi (Photo credit should read MARTIN BERNETTI/AFP/Getty Images) An Iraqi man holds an edition of Iraqi daily newspaper Azzaman displaying pictures of US presidential candidates Donald Trump and Hillary Clinton in Baghdad on November 9, 2016. Billionaire populist Donald Trump, tapping into an electorate fed up with Washington insiders, was on the verge of a shock victory over Hillary Clinton in a historic US presidential election that sent world markets into meltdown. / AFP / SABAH ARAR (Photo credit should read SABAH ARAR/AFP/Getty Images) Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

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