Ruth Ben-Ghiat is a frequent contributor to CNN Opinion, and professor of history and Italian studies at New York University. She is currently working on a book entitled "Strongmen: From Mussolini to Trump." The opinions expressed in this commentary are solely those of the author.

(CNN) Sometimes political change happens suddenly. You wake up, and a military junta has taken over your country, or some other kind of revolution has happened. But other times, the climate shifts little by little. A few big gestures of aggression, and then things settle down. Then the cycle repeats, until one day the tipping point is reached and you find your democracy has been transformed into an autocracy.

We're at serious risk of this happening in America.

Trump's first 100 days have been a lesson for him in what he can and cannot easily do. He's followed the authoritarian playbook in attacking those sectors of society that uphold the value of evidence (the judiciary , the press, researchers). He's purged the bureaucracy; hired family members (who thumb their noses at conflicts of interest); bullied critics on Twitter ; and incited a climate of hatred toward targeted groups ( Muslims , Latinos, immigrants , and more).

Many of those attacks have been successfully thwarted thus far. Trump has faced significant and sustained pushback to his programs and methods -- including cherished measures like the travel ban and repealing and replacing Obamacare -- from the press and the judiciary, and even by factions of his own party. Civic engagement and political activism have also grown exponentially in response to the dangers to our freedoms that he represents -- as has funding and support f or investigative journalism.

Authoritarians, however, are most dangerous at such moments, when they feel vulnerable. With the #TrumpRussia scandal widening, we can expect the White House to become much more aggressive in imposing its agendas. Non-whites will bear the brunt of this, under the guise of crackdowns on immigration, crime and drugs. Certainly, drugs are a flashpoint of late, because of President Trump's invitation to his counterpart in the Philippines Rodrigo Duterte -- whose regime's extrajudicial killings in his "war on drugs" and other human rights abuses have made him notorious -- to visit the White House.

Political change announced itself formally with the blitz of executive orders that followed President Donald Trump's January 2017 inauguration. Kellyanne Conway's tweet f rom that period remains all too relevant. "Get used to it. @POTUS is a man of action and impact. Promises made, promises kept. Shock to the system. And he's just getting started."

We should get ready for another round of such "shocks": Trump's been sending signals that he's preparing to accelerate his consolidation of personal power. In an interview Friday with Fox News, Trump criticized the "archaic" rules of the House and Senate, saying "maybe at some point we are going to have to take these rules on, because for the good of the nation things are going to have to be different."

His attitude toward filibusters received the most press, but in discussing the "bad concepts" under the current "archaic" system, he also mentioned voting. Perhaps Trump meant voting procedures in the Senate -- here, as so often, he's evasive. In any case, his questioning of a main index of democracy -- allowing our elected representatives to cast votes on our behalf -- should be front-page news.

Like many demagogues before him, Trump bills himself as a modernizer who can "repair" a broken system. Apparently, checks and balances are in the same category for him as old bridges and leaky borders: things that need fixing to work efficiently. Ian Bassin, a a former White House associate counsel and Executive Director of United to Protect Democracy, a watchdog organization led by former White House and administration lawyers and constitutional litigators, noted to me that if Trump isn't content with upending democratic norms and starts to change their underlying laws, "there's no end to how much power he could try to amass."

But, many might ask, wouldn't government run better in a more streamlined manner, allowing Trump to manage by decree, as he does in his business life? A supporter interviewed by the Washington Post at his Harrisburg, Pennsylvania rally, thinks so . "I wish we had no parties -- they just lock into left or right, and nothing gets done. [Trump] wants to fix stuff." It's a common theme heard among Trump's followers: just let him come in and run things "like a business."

But there's a name for a system with no parties and a strongman leader at the helm: dictatorship.

As for Trump's other main targets, his staunch ally, National Rifle Association head Wayne LaPierre, summed them up well at the NRA's Leadership Forum (where President Trump also spoke): "Academic elites, political elites, and media elites are America's greatest domestic threats." This weekend, while the media celebrated its resilience at the White House Correspondents' Dinner, the White House, according to chief of staff Reince Priebus, has "looked at" how to change constitutional law to restrict press freedoms. Talking about changing liberal laws is another ominous sign of Trump's aspiration to strongman status.

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Authoritarians are often ungenerous people, but they do give us one gift: they tell us what they are going to do before they do it, both as an intimidation and as a challenge. Trump always follows this rule. At his weekend rally, he recited the lyrics of a song by Al Wilson about a woman who rescues an ailing snake, only to find that as soon as the snake feels better he bites her. When she protests, he grins and says, "Oh shut up. You knew damn well I was a snake before you took me in."

Like the woman who helped the snake, we have been warned. Democracy dies not only in darkness, but also with advance notice, in clear view. Trump's letting us know that he intends to act. It's up to all of us to make sure he is not successful.