Candidate Trump's appeal came from his willingness to break political norms. But now that he's president, could his actions be violating democratic norms?

That's a topic Harvard professors Steven Levitsky and Daniel Ziblatt explore in their new book, "How Democracies Die." They study how authoritarian regimes have taken hold in other parts of the world, and argue that there are warning signs that some of America's institutions and norms are growing weaker and weaker — putting our democracy at risk.

Levitsky and Ziblatt joined "Boston Public Radio" to discuss the book and their research. Some highlights of the conversation are below.

On why they decided to write the book:

Ziblatt: It was the tenor of the presidential campaign that made us think to write this book. The things that attracted us or made us think there was a real threat here, in [Trump's] rhetoric at least, was his willingness to go after the media, his willingness to challenge the results of elections, or he threatened this, his accusation that his political rival was a criminal, and his willingness to condone violence at his political rallies. We really thought, 'these are the hallmarks'. We've studied democracies and democracies in crisis around the world, and this is something we had seen before. It was a movie we had seen before that usually doesn't have a very good ending. That made us very nervous.

On how authoritarian regimes take power in the 20th century:

Levitsky: Coups were the old way of killing democracies. Back in the Cold War, three out of four democracies died at the hands of men with guns, by coups. Since the end of the Cold War, the solid majority of democratic breakdowns have taken place at the hands of elected leaders — elected prime ministers and elected presidents — who use the very institutions to eviscerate it. 

I'll give you some examples that are not immediately comparable to the United States ... in the sense that the U.S. has much stronger institutions. Three well-known examples: Hugo Chavez was freely elected, the first few years of his government were democratic [and] touted opposition and the free press, but gradually eviscerated democratic institutions. Erdogan in Turkey is another case. The AKP was initially freely elected, democratically elected, and over the course of over a decade eroded democracy. A third is Hungary, a pretty solid democracy where the government of Viktor Orbán has — not as much as the government of Turkey — but has chipped away at what used to be a level playing field.

On how American institutions have fared, one year into the Trump presidency:

Ziblatt: The American system is very different from these other countries. That's a point we make in the book. There are these warning signs, but a system of checks and balances: not only a fixed term for the president but also the different branches of government, federalism — all these are constraints on power, were designed as constraints on power, so the president could not overreach in ways we might fear could happen, undermining democracy. In many ways our checks and balances appear, in the first year of the presidency of Donald Trump, to have worked pretty well. The judicial branch and legal institutions have served as a check. Social institutions, media, free media has played an important role. [There's ] federalism: blue states take very different stances than what the president wants. These all serve as checks.

One thing we're nervous about, though, is the role of Congress. Congress is designed to be a constitutional guard dog, and in many ways, the Republican-dominated Congress has turned into more of a lapdog for the president used as a shield to protect the president.

On why they're hopeful for the future:

Levitsky: Our democracy is hard to kill. We do still have very strong democratic institutions. We're not Turkey, we're not Hungary, we're not Venezuela. We can behave quite recklessly and irresponsibly and probably still muddle through that. We think it's very important that we not take our democracy for granted, that we learn lessons from democratic crises in other countries. But we do have a really strong foundation.

The other thing is, as bad as this country has dealt at times, for most of our history, with race, and as difficult a time as we've had in the past with immigration, we've actually done better than most societies in the world. We are a society that has a lot of experience in assimilation, in dealing with ethnic and cultural diversity. We've done it in the past, we did it fairly successfully in the early 20th century. The big challenge we face is becoming the world's first truly multi-ethnic democracy. And I actually think we have a pretty decent chance to pull it off.

Click the audio player above to hear the full conversation.