On Sunday, Majority Leader Sen. Mitch McConnell (R-Ky.) tried to reassure voters about Donald Trump. “[W]what protects us in this country against big mistakes being made is the structure, the Constitution, the institutions,” he said. “No matter how unusual a personality may be who gets elected to office, there are constraints in this country. You don’t get to do anything you want to. So I’m very optimistic about America. I’m not depressed about the nature of the debate.”

Then on CBS’s This Morning, McConnell gave some advice to Donald Trump: “I’d like to see a more studious approach.” He continued, “I think that winning the White House is about more than just entertaining a large audience. I think the American people would also like to see him fill in the blanks.”

We would like to think McConnell is correct. If Trump studies up on some issues and uses scripted speeches, he’ll be fine. If he gets elected, Congress will stop him from doing anything too nutty. That sounds good, but it’s not remotely true.

As for studying, Trump seems neither inclined to read even briefing materials or learn from those more knowledgeable. Even his scripted speeches, most notably his foreign policy remarks (with the Russian ambassador front and center), are incoherent. He does not attract the best and the brightest to read the speeches; and, moreover, they still reflect his dangerous isolationist and protectionist instincts. A scripted Trump is still Trump.

McConnell is right about one thing: Trump’s ad-lib interviews are worse, and generally disturbing. His impromptu attacks on fellow Republicans don’t vanish simply because he gave an energy speech a few days earlier.

As for the issue of governance, the Constitution does not protect the American people from a commander-in-chief with atrocious judgment or a president who acts unilaterally, eviscerating the limits on the executive. That was the lesson of the Obama years, no? If the president is bent on misusing the executive branch (e.g. the IRS), the remedy is usually after the fact. Former CIA and NSA director Michael Hayden reminds us that Trump’s rhetoric helps the enemy’s recruitment. It can likewise demoralize friends. The president matters, more than any other individual on the planet, when it comes to our safety, security and prosperity and to that of the Free World.

Moreover, Trump repeatedly shows contempt for the judiciary, as he did over the Memorial Day holiday in excoriating the judge in the Trump U litigation who ordered documents to be unsealed. He and his spokesman suggest the judge is biased against Trump because she is Hispanic. Does anyone think he would be more inclined to respect courts if he wins? Surely not.

Even worse, McConnell’s own troops won’t be all that inclined to stop Trump. If Trump is extracting pledges of support now, imagine what he’ll do when he has the powers of the White House at his disposal. You’ll have Republican senators assisting Trump as he wreaks havoc on the budget, our tax code and more. And, of course, with Trump at the top of the ticket there is a very good chance Sen. Charles E. Schumer (D-N.Y.), not McConnell, will be majority leader.

McConnell has a job to do as majority leader. He has members he wants reelected and who cannot go to war with Trump. To his credit, McConnell is avoiding fawning over Trump, unlike some fellow Republicans who seem bent on destroying their credibility. Nevertheless, the rest of us should take his soothing words with a large grain of salt. A narcissist with an authoritarian streak, one surrounded by shady characters with foreign connections and unable to separate Internet rumor from fact can do great damage to America’s economy, military and assorted institutions. He’s already done untold damage to the political debate, rendering it even more vulgar and nasty than it was before he threw his hat into the ring. It’s why it is critical to keep him out of the White House.