Checks and balances may not restrain him.
Some arguments for a Donald Trump presidency are worse than others. For example arguing that we should prefer Trump because he'd be a more entertaining president than Clinton. And that no matter how bad Trump is, the checks and balances in the system will keep him on a tight leash.
The entertainment factor has been cited by several people, most notably right-wing pundit Jonah Goldberg
(although he says he won't vote for Trump himself). Goldberg's argument: "Clinton is boring. She's as fun as changing shelf paper on a Saturday afternoon," whereas "Trump: the Movie? That could be a wild ride."
Choosing a president based on the entertainment value sounds marginally less illogical if you buy the argument expressed by Rush Limbaugh, Senator Mitch McConnell
and some voters (according to interviews) that Trump's authoritarian view of the presidency is unimportant: the U.S. president is not a dictator so the federal system automatically limits what Trump might do. It would be nice if that were true, but it isn't.
As the blogger Hilzoy once put it, when we say "the president can't do X" we usually mean something like "the president has no legal or constitutional authority to do X" or "there's no precedent for the president doing X." History proves that's not much of an obstacle to a determined Oval Office resident.
Take George W. Bush. If someone had claimed in 1999 that the president has the authority to lock up people indefinitely, including American citizens, without any hearing, without any evidence, based on nothing but his own decree they were enemies of the state, I'd have laughed. Locking up people without trial is one of the hallmarks of dictatorship, and the American president doesn't have that power.
Or so I thought. Because when Bush claimed he could lock up "enemy combatants" based on nothing but his own assertion they were a threat, those people (the overwhelming majority of whom were innocent) were indeed locked up. There were no checks, no balances; the rest of the government acted as if Bush was stating an established constitutional truth. The Supreme Court eventually set some limits on the enemy-combatant policy, but we still have 80 enemy combatants imprisoned in Guantamo Bay. Far from fighting this expansion of presidential power, McConnell is among the Republicans who shriek with outrage at calls to shut Gitmo down.
Or consider the 1960s. Back then the CIA operated under an absolute ban against conducting intelligence operations on U.S. soil. Nevertheless, when President Johnson ordered the CIA to spy on the U.S. anti-war movement, the CIA did it. Like Bush, it was something Johnson couldn't do—until he went ahead and did it.
This isn't surprising. For a variety of reasons, the president's powers have grown steadily since Washington took office (Arthur Schlesinger's The Imperial Presidency
has some good history on this). I imagine one simple reason is that for people under the Executive Branch, an order from the president packs a lot of weight, even if the order is illegal. If the president says "Jump!" plenty of people would react with "How high?" rather than "Mr. President, can you cite the legal authority that requires me to jump."
I can understand ordinary voters being naive enough to think Trump can't take on more power than the law allows. With political veterans such as McConnell and Limbaugh, it's harder to believe they're that clueless—but then again, they wouldn't be the first political players to imagine they could leash the unleashable. Or possibly they've just accepted Trump will be the nominee, and so they need to reassure the non-Republican voters he's not so bad. After all, from the Limbaugh/McConnell perspective Trump's a much better choice than Clinton or Sanders. He's more more likely to sign Republican-backed bills and appoint conservatives to the Supreme Court, and he obviously has no problem with dumping on Muslims and Latinos. If he proves to be a disastrous president, their wealth and connections will insulate them from the worst of the disaster. So why wouldn't they support him?
From my perspective, even if all Trump did in office was sign Republican-backed bills into law, that would be bad enough. If he does, in fact, act on his wilder campaign promises, I think it'll be worse.
Contrary to Jonah Goldberg, I'll happily vote for boring.