President Joe Biden and former Ambassador Nikki Haley don’t agree on much, but they’ve apparently found one notable area of common ground: They think Donald Trump’s many cognitive missteps are worth talking about.

To be sure, this isn’t altogether new. As we discussed a few months ago, the former president raised plenty of eyebrows in the fall after falsely telling an audience that Hungary’s Viktor Orbán is “the leader of Turkey,” suggesting Biden might be responsible for starting “World War II,” confusing Jeb Bush and George W. Bush, mixing up Biden and Barack Obama, and repeatedly declaring that Hungary borders Russia.

These questions returned to the fore over the weekend, however, after the likely GOP nominee twice confused Haley with Speaker Emerita Nancy Pelosi during a Friday night event in New Hampshire.

This came on the heels of related instances in which Trump falsely claimed he was president in 2021, and confusing North Korea’s Kim Jong Un and China’s Xi Jinping.

Circling back to our earlier coverage, it’s difficult to speculate about the explanation for these missteps. Maybe the Republican — who’s notoriously vain about wearing eyeglasses — misread his trusted teleprompter. Maybe he misspeaks when fatigued. Maybe the errors were related to his age. Maybe he’s made roughly the same number of verbal mistakes we all make from time to time but Trump’s incidents stand out because he has a vastly larger platform and receives greater scrutiny.

The trouble, however, is that the frontrunner for the Republican presidential nomination is also going after the Democratic incumbent as someone experiencing cognitive decline. The New York Times recently noted that one of Trump’s routine comedic bits at his rallies features him impersonating Biden “with an over-the-top caricature” mocking the president’s age.

With droopy eyelids and mouth agape, Mr. Trump stammers and mumbles. He squints. His arms flap. He shuffles his feet and wanders laggardly across the stage. A burst of laughter and applause erupts from the crowd as he feigns confusion by turning and pointing to invisible supporters, as if he does not realize his back is to them.

In other words, the likely Republican nominee, who would turn 80 partway through his second term if elected again, is going after his slightly older rival as if Biden were a doddering old fool. To bolster their case, Trump and his allies routinely point to examples of the Democratic president misspeaking, concluding that Biden is “cognitively impaired” and “in no condition to lead.”

And if Trump were a model of eloquence who never made verbal mistakes, this might be a more potent line of attack. But it’s a much tougher sell when the likely GOP nominee makes the same kind of missteps that Biden makes — and everyone notices.

This post updates our related earlier coverage.