You could almost hear a collective groan go up when Barack Obama announced that he planned to deal with his recent setbacks by “speaking directly to the American people.” After 158 interviews and 411 speeches in 2009, who’s clamoring to hear more from a president whose microphone addiction rivals Bill Clinton’s?

If you think we’ve got it bad, pity the Venezuelans, whose strongman president, Hugo Chavez, rules the airwaves with his own talk show. “Hello, President!” airs Sundays, sometimes for up to eight hours, and it features Chavez singing, insulting his enemies, giving shout-outs to Fidel Castro, and even, on one occasion, describing a gut-wrenching bout of diarrhea he’d had while filming the show.

From afar, the Chavez regime seems like something from a comic dystopian novel. But it’s no laughing matter.

Last week, Chavez ordered six TV stations off the air, ostensibly for refusing to air his frequent and interminable speeches. His real motive was to squelch dissent amid raging inflation, rolling blackouts, and growing public disgust with his lawless rule. So far, two students have died in anti-censorship protests.

Undaunted, the combative caudillo declared that Twitter criticism of the president “is terrorism,” and the protesters are “seeking death.”

Chavez is only the most recent example of our southern neighbors’ long-running problem with authoritarian presidents who decry U.S. “imperialism” as they push for increasingly imperial powers.

Ironically, though, when Latin American autocrats blame the region’s problems on Yankee influence, they may be more right than they know.

When the region’s former Spanish and Portuguese colonies gained independence in the early 19th century, they followed the U.S. example by adopting presidential systems. Instead of copying the British parliamentary system, where the chief executive is elected by, and accountable to, a legislative majority, they opted for the American model, with an independent executive who’s harder to remove, and can invoke his electoral “mandate” to pose as the living embodiment of the popular will.

In an influential 1990 article, “The Perils of Presidentialism,” political scientist Juan Linz argued that presidential systems are especially bad for developing countries, because they encourage cults of personality and foster instability. Subsequent studies have bolstered Linz’s insights, showing that presidential systems are more prone to corruption and far more likely to suffer catastrophic breakdowns than parliamentary ones.

Presidentialism’s perils are apparent throughout Latin America today, where populist despots invoke “democracy” in the service of one-man rule.

In recent years, Bolivia’s Evo Morales, leader of the “Movement for Socialism” (acronym “MAS,” for “more”) forced constitutional changes that overturned a ban on his re-election and enhanced state control of the economy. Ecuador’s Rafael Correa, a Chavez ally, frequently breaks into prime-time programming with Big Brother-style attacks on his opponents. Correa too has overturned presidential term limits and gained the power to dissolve the legislature.

Yet the American president retains staggering powers at home and abroad. He can send the world’s most powerful military into battle at will, Congress’ power “to declare war” notwithstanding; and he can reshape vast areas of American life unilaterally via executive order.

That’s not to suggest that we ought to hold a constitutional convention and replace our presidential system with a parliamentary one. American-style separation of powers has its advantages, after all.

Without it, for example, there’s little doubt we’d have had socialized medicine long ago. Yale’s Ted Marmor, a leading historian of the U.S. health care system, argues that the main reason we don’t is that our Constitution’s framers rejected a parliamentary regime in which “electoral victories typically produce policy majorities.”

But we should remain vigilant about the peculiar dangers of our system. The narcissistic despots who plague our southern neighbors offer a cautionary tale for those willing to cede still more power to populist presidents.

The lesson for all of us, north and south of the border, is watch our presidents closely, and check them when they try to slip their constitutional bonds.