At a White House event last week, Donald Trump boasted, “The poll numbers are through the roof. Our poll numbers are great.”

Perhaps the president should’ve picked something else to brag about.

The latest national CNN poll, released yesterday, showed Trump’s approval rating down to a woeful 36%, the lowest it’s been in CNN polling in several months. Among self-identified independent voters, the president’s support is down to just 31% – an all-time low for Trump.

What’s more, it’s not the only new poll showing Trump below the 40% threshold: a national Quinnipiac poll, also released yesterday, found the president’s support down to 38%, The same results showed Trump struggling in a variety of key areas: 60% believe the Republican is not honest, 65% believe he is not level-headed, and 55% believe he not “fit to be president.”

But this was the result from the Quinnipiac report that jumped out at me:

Do you think that President Trump is mentally stable, or not? Yes, he’s stable: 48%

No, he’s not: 42%

The fact that a plurality of Americans said yes may seem like fairly good news for the president, but that’s a rather generous way of looking at the results. For one thing, Trump couldn’t quite crack the 50% mark on this question, which is hardly reassuring.

For another, we’ve reached the point in American history at which a major independent pollster feels justified asking the public about a sitting president’s mental stability.

For what it’s worth, Trump seems aware of the questions about his acuity, especially in light of Bob Woodward’s new book, and the president last week started offering proof of his mental health. Here’s what Trump told reporters aboard Air Force One last week:

“I can’t get up and talk in front of a crowd – many times without notes – for an hour and 25 minutes and get the biggest crowds in the history of politics…. You don’t get up and do that because you don’t know how to think or talk. You can only do that if you’re at a very, very high level.”

A day earlier, he said something very similar to a crowd in Montana: “I stand up here giving speeches for an hour-and-a-half, many times without notes. And then they say, ‘He’s lost it.” And yet we have 25,000 people showing up to speeches.”

To the extent that reality matters, Trump routinely delivers long, rambling, spectacularly dishonest speeches to partisan audiences, usually with the benefit of a teleprompter. If the president is looking for proof of his mental stability, perhaps he should look elsewhere.