Donald Trump is pretty obviously an incipient tinpot dictator. He's got the demagogue's knack for both playing off and encouraging the worst instincts of his supporters, including violent reprisals against scapegoats. He's got wide support among authoritarians. He's even got the taste for garish prestige construction projects.

What makes a Trump presidency genuinely terrifying, however, is the prospect of him at the helm of the American security apparatus. That could turn a merely bad presidency into a huge advance of authoritarianism, and perhaps the beginning of the end of constitutional democracy in the United States.

That sounds extreme, and it's true that in a country with reasonably strong democratic institutions, a strong ethic of professionalism in the federal bureaucracy, and universal respect for the rule of law, even the most cunning authoritarian president could do only so much.

But the United States is not that country. While much of the government basically functions pretty well, the same cannot be said of the most important bulwarks against a Trump takeover: the security apparatus. This is, roughly speaking, the mass of agencies that make up the Intelligence Community (including the CIA, NSA, NRO, and so forth), plus the parts of the military that aren't dedicated to overseas actions.

It's been almost two years since the CIA, as Sen. Dianne Feinstein (D-Calif.) detailed in an explosive speech on the Senate floor, illegally spied on the Senate intelligence oversight committee in a clear attempt to sandbag the committee's investigation into the agency's (also extremely illegal) torture program. Though the executive summary of that report, consisting of about one-tenth of the 6,000 pages, was released to some fanfare in December 2014, the whole episode has been a smashing victory for the CIA.

After a brief lull of unfavorable media coverage, torture largely faded from view. Nobody was prosecuted or indicted, even those who admitted on national television to destruction of evidence. President Obama himself delivered a condescending lecture that we should not be too "sanctimonious" about the fact that "we tortured some folks." And after the 2014 lame duck session, Republicans took control of the Senate partly on the strength of defeating one of two strong critics of torture, Mark Udall (D-Colo.), and promptly installed a CIA lickspittle as chairman of the intelligence committee.

Elsewhere, it's been almost three years since Edward Snowden's revelation of the NSA dragnet surveillance program, an obvious violation of the Fourth Amendment that was repeatedly ruled illegal in federal court. Though Congress did pass an NSA reform bill last year, it was weak tea at best. The bill "does absolutely nothing to restrain the vast majority of the intrusive surveillance revealed by Snowden," as Dan Froomkin writes. Most of the dragnet is still there.

Though both these episodes were yet more crushing blows to the rule of law, at least the CIA does not currently torture people. However: Trump (and Marco Rubio) promise to bring back torture. It "works," Trump says. He's flat wrong when it comes to interrogation, but torture is actually quite good for intimidation and extraction of false confessions.

So, we've got one agency with a proven history of brutal thuggery and spying on its congressional overseers, another with the capability to spy on virtually all electronic communication, and God only knows what else in the rest of the secret government. It's highly unlikely that these organizations would mount any sort of serious revolt should Trump carry out his public insinuations that he would intimidate rivals using their power. Chances are somewhat better they would resist an actual coup d'etat, but it's a thin reed indeed to hang one's hopes on.

Democrats bear a significant share of the blame for this situation. President George W. Bush, Vice President Cheney, and their pet lawyers like David Addington and John Yoo were largely responsible for mutating the security apparatus into its current dangerous form, but Democrats had a golden opportunity to fix that in 2009-10, with huge congressional majorities and a strong mandate to reject Bush's policies. There were some halting steps in that direction, but in part because many key Democrats are knee-jerk defenders of the security apparatus (including Feinstein, ironically), it went nowhere.

Now, in all likelihood, President Trump probably wouldn't actually try to overthrow the Constitution and install himself as dictator-for-life. But I view it as a virtual certainty that he would go after critics and political rivals, and a strong possibility that he would attempt Putin- or Erdogan-style moves to keep himself in power for as long as possible. With constitutional governance visibly wobbly, and a 4-4 tie between liberals and conservatives at the Supreme Court likely to continue indefinitely, it's hard to see what would stop him.

For that, we have the chowderhead elites of both parties to thank.