Danielle S. Allen, a Government professor and director of the Edmond J. Safra Center for Ethics, called on Americans across the political spectrum to organize against businessman Donald J. Trump’s presidential campaign in a Sunday op-ed that has generated widespread reaction.

Allen said she found the need to write the op-ed for The Washington Post after Trump’s victory in Saturday’s Republican primary in South Carolina. Describing the primary as a “turning point,” Allen wrote in the piece that voters should recognize that there is not much time left to change the outcome of the Republican presidential nomination contest.

In the op-ed, which now has over 5000 online comments, Allen examined the dangers she perceived in Trump’s rise to political prominence, which she believes is a product of growing divisions in the United States. Instead of choosing not to challenge Trump, Americans must support “coordination across party lines and across divisions within parties,” Allen wrote.

“We, the people, need to find somewhere, buried in the recesses of our fading memories, the capacity to make common cause against this formidable threat to our equally shared liberties,” she wrote. “The time is now.”

Allen said she has received a wide range of opinions in response to her article, from the candidate’s supporters as well as his critics.

She wrote in her piece that Trump’s popularity has allowed her to understand how Nazi dictator Adolf Hitler was able to take control of Germany in the early 1930s. In an interview, Allen said she is not focused on exploring the direct comparison between Hitler and Trump, a point she also made in her op-ed.

“The fact that particular historical moments can teach us things that help us understand different moments doesn’t mean that there is a straight comparison between them,” she said. “The thing that requires comparison is the question of when and how do demagogues acquire power. That’s what is the relevant comparison.”

History professor Charles S. Maier ’60, a specialist in German history and former Crimson editorial chair, said the underlying question in Allen’s op-ed was over whether divisions in the United States today mirror those of the Weimar Republic, the democratic German state that preceded the Nazi regime.

While Maier said he does not believe the comparison is accurate, he said the rhetoric Trump uses is pervasive in Western politics.

“There are candidates who appeal to this sort of populism, anti-foreign impulse of feeling that their governments are too remote and don’t care about them,” he said. “That is a widespread feeling throughout western Europe and the United States, and I think in that sense it produces ugly responses that stigmatize foreigners.”