From the lips of an authoritarian, blustery contender for the highest executive office in the land come a steady stream of threats, insults and big lies. At huge rallies, he eggs on violence and stokes popular hatred and divisions. He manipulates media outlets and bars reporters who ask tough questions. A candidate who rose to prominence questioning the legitimacy and patriotism of the sitting president threatens, if elected, to deploy vast powers of government against judges and political opponents in his own and the other major political party. He promises to lock up, deport and exclude from the country entire demonized categories of people, while rolling back the rights of minorities, gays and workers. He boasts about ignorance of world affairs, calls on foreign powers to help him defeat domestic competitors and pushes to overturn his country’s longstanding international agreements and alliances.

What country are we talking about? Kim Jong-un’s North Korea? Idi Amin’s Uganda? Chavez’s Venezuela? Mussolini’s Italy? No, amazingly enough, it is the United States of America in 2016, where Donald Trump, a radical ethno-nationalist, has taken the helm of the once venerable Republican Party. In recent years, GOP elites have made promises they could not keep and moved so far to the ultra-free-market right that most of their own voters have tossed them aside in favor of a fraudulent huckster who got close to $2 billion in free media coverage to insult and defeat 16 competitors in the GOP primaries. Recently, those GOPers who did not avoid their 2016 Cleveland convention proceeded to crown Leader Trump during an early 1930s-style dramatization of dark threats and violence.

My profession, political science, has learned that the promises politicians make in high-profile elections should be taken seriously. If they win government power, they almost always carry through. Prodded to the left, Hillary Clinton promises to abandon free trade negotiations and push jobs investments — and she would. Trump would keep his dark promises, too. In the White House, he would unleash four years of domestic turmoil and international clashes, undermining social cohesion and America’s standing in the world.

For Trump’s GOP enablers, the eventual reputational and electoral consequences would be disastrous — and arguably well deserved — but not until after Trump and right-wing Republicans visited enormous and largely irreparable harm on the rest of us. Democrats, reasonable Republicans and independents alike do not need or deserve this. No matter what other candidates we support this November, we need to come together to vote for Hillary Clinton to stop Trump.

Trumpism is so shocking, such a departure from the ideals and norms of conservative or liberal politics that many observers and voters seem to treat it as a bad joke, presuming The Donald has no realistic chance to win. That is just plain wrong. In a highly polarized electorate, many Republicans believe, falsely, they could benefit from a Trump victory. Major GOP blocs — Christian rightists, gun champions and tax cutters — have fallen in line, and they will soon be buoyed by hundreds of millions in contributions from right-wing millionaires and billionaires who hope to manipulate and control Trump. Conservative elites always delude themselves into believing they can do that when racist populists appear.

In an attempt to reprise the 1968 “law and order” election, Trump is counting on anxieties about immigration and unpredictable violent atrocities. Immigrants have arrived in America in large numbers over recent decades, most of them from Mexico, Central America and Asia. Undocumented immigration has actually sharply declined, and research shows that newcomers are embracing core American values and contributing to economic growth, just like earlier immigrants. But Trump knows that in many areas, older whites do not perceive these realities. By denouncing Mexicans as “rapists” and job killers, he hopes to stoke and benefit from ethnic fears. Here in Maine, a mini-Trump governor has done the same thing.

Trump also gleefully seeks benefit from international violence. As Islamic State terrorists are pummeled militarily in the Middle East, they commit or inspire atrocities from France to Bangladesh — and each horror gets days of media coverage. In the United States, military-style guns are readily available to troubled young men, ranging from the Colorado and Newtown teenagers to anti-abortion zealots to Internet-inspired Islamic attackers such as those who have struck from Boston to Orlando. We can be sure more crazies will strike again, giving Trump yet more chances to pound his chest and brag on Twitter.

So, yes, Trump and Trumpism could win in November, unless the rest of us set aside our political differences and elect, instead, a sane and extraordinarily well-prepared candidate, Hillary Rodham Clinton.

Many Americans, I realize, have bought into propaganda questioning Clinton’s basic honesty. Her style is guarded, and she is no less given to downplaying her mistakes than any other longstanding politician. But Clinton has been a liberal and progressive policy champion for decades, much more so than her husband. And I know her strengths from personal experience as well as academic research. Many years ago, in early 1995, I briefly met Hillary in person. I had imbibed so many demonizing attacks that I expected to encounter an unpleasant, haughty woman. But when I ended up at the same supper table with First Lady Hillary Clinton and her young daughter, Chelsea, I met a warm, funny, down-to-earth person, clearly a wonderful mother, who un-defensively engaged me, a critic of her 1994 health reform efforts, with curiosity about what my research showed she might do better in continuing efforts.

Hillary Clinton is, in short, far from the caricature her enemies are pushing. She is thoughtful and well prepared. She learns, listens and keeps at it. She is the un-Trump. And she is by far the better choice for president in 2016 — actually, the only sane choice for all voters who care about America’s shared future.

A longtime summer resident and taxpayer in Maine, Theda Skocpol is the Victor S. Thomas Professor of Government and Sociology at Harvard University and the national director of the Scholars Strategy Network. This piece draws on her research about American and cross-national politics but primarily expresses her personal views as a citizen and voter and not the views of any organization. Scholars Strategy Network members’ columns appear in the BDN every other week.