Donald Trump. Alex Wong/Getty Images A Harvard University professor published an editorial in The Washington Post on Sunday that compared the surprising rise of Republican presidential candidate to Adolf Hitler seizing power in Germany.

"Like any number of us raised in the late 20th century, I have spent my life perplexed about exactly how Hitler could have come to power in Germany," professor and political theorist Danielle Allen wrote.

"Watching Donald Trump's rise, I now understand," she added.

She then went on to explain "how a demagogic opportunist can exploit a divided country." She urged Trump's critics not to stand by passively as he gains support among Republican primary voters.

Allen wrote:

Trump is rising by taking advantage of a divided country. The truth is that the vast majority of voting Americans think that Trump is unacceptable as a presidential candidate, but we are split by strong partisan ideologies and cannot coordinate a solution to stop him. Similarly, a significant part of voting Republicans think that Trump is unacceptable, but they too, thus far, have been unable to coordinate a solution. Trump is exploiting the fact that we cannot unite across our ideological divides.

Hitler rose to power on a nationalist message. He told the German people that they were exceptional and played on feelings of disenfranchisement.

Allen also called for Ohio Gov. John Kasich and retired neurosurgeon Ben Carson to drop out of the race for the so that their support could consolidate behind Florida Sen. Marco Rubio, who she argued could pose a viable threat to Trump's candidacy.