This long piece by David Frum is worth reading in full - How to Build an Autocracy. A couple of snippets:
Outside the Islamic world, the 21st century is not an era of ideology. The grand utopian visions of the 19th century have passed out of fashion. The nightmare totalitarian projects of the 20th have been overthrown or have disintegrated, leaving behind only outdated remnants: North Korea, Cuba. What is spreading today is repressive kleptocracy, led by rulers motivated by greed rather than by the deranged idealism of Hitler or Stalin or Mao. Such rulers rely less on terror and more on rule-twisting, the manipulation of information, and the co-optation of elites.
The United States is of course a very robust democracy. Yet no human contrivance is tamper-proof, a constitutional democracy least of all. Some features of the American system hugely inhibit the abuse of office: the separation of powers within the federal government; the division of responsibilities between the federal government and the states. Federal agencies pride themselves on their independence; the court system is huge, complex, and resistant to improper influence.
Yet the American system is also perforated by vulnerabilities no less dangerous for being so familiar. Supreme among those vulnerabilities is reliance on the personal qualities of the man or woman who wields the awesome powers of the presidency. A British prime minister can lose power in minutes if he or she forfeits the confidence of the majority in Parliament. The president of the United States, on the other hand, is restrained first and foremost by his own ethics and public spirit. What happens if somebody comes to the high office lacking those qualities?
Over the past generation, we have seen ominous indicators of a breakdown of the American political system: the willingness of congressional Republicans to push the United States to the brink of a default on its national obligations in 2013 in order to score a point in budget negotiations; Barack Obama’s assertion of a unilateral executive power to confer legal status upon millions of people illegally present in the United States—despite his own prior acknowledgment that no such power existed.
Donald Trump, however, represents something much more radical. A president who plausibly owes his office at least in part to a clandestine intervention by a hostile foreign intelligence service? Who uses the bully pulpit to target individual critics? Who creates blind trusts that are not blind, invites his children to commingle private and public business, and somehow gets the unhappy members of his own political party either to endorse his choices or shrug them off? If this were happening in Honduras, we’d know what to call it. It’s happening here instead, and so we are baffled.