Donald Trump has long been taken a keen interest in who should and shouldn’t be “allowed” to run against him. In late 2015, for example, the future president helped promote the idea that Hillary Clinton shouldn’t “even be allowed” to run for national office.

A month later, the Republican pushed the idea that Ted Cruz shouldn’t have been “allowed” to run for the GOP’s 2016 presidential nomination. Two months later, Trump said John Kasich shouldn’t have been “allowed” to run against him in a Pennsylvania primary.

Even during his pre-inaugural transition period, the then-president-elect, apropos of nothing, remained focused on Clinton, insisting after the election that his former rival shouldn’t have been “allowed” to run against him.

This afternoon, Trump apparently concluded that his 2020 opponent shouldn’t be “allowed” challenge him, either. Here’s what he published to Twitter:

“Wow!!! NOW DO SOMETHING ABOUT THIS, THE BIGGEST OF ALL POLITICAL SCANDALS (IN HISTORY)!!! BIDEN, OBAMA AND CROOKED HILLARY LED THIS TREASONOUS PLOT!!! BIDEN SHOULDN’T BE ALLOWED TO RUN – GOT CAUGHT!!!”

It’s worth emphasizing that this is exactly how the president’s missive appeared online: the all-caps text, the 12 exclamation points, etc., were all in the original. It’s also worth noting that Trump’s message was connected to a tweet originally published by an apparent Trump supporter in January 2018 — nearly three years ago.

In other words, the struggling president is recycling a strange, old, discredited content as part of an online tantrum, all in the hopes of arguing that the candidate who appears to be beating him shouldn’t be permitted on the ballot.

To the extent that reality still has meaning, Trump’s weird missive is plainly absurd. He’s referring to a “scandal” that does not exist, “treason” that was never committed, and a “plot” that remains a figment of the Republican’s imagination. The president expects people to believe that his 2020 rival “got caught,” but he’s never made any real effort to explain what it was, exactly, he thinks the former vice president was caught doing.

But stepping back, the fact that Trump has no idea what he’s talking about is only part of the problem. The incumbent, facing questions about the effects of his medications, and confronted with discouraging polling data, appears to be having some kind of meltdown — or more accurately, the latest in a series of meltdowns.

When a president is reduced to insisting that the opponent beating him shouldn’t be allowed to compete, it’s generally a sign that things aren’t going well. There’s no getting around the fact that denying the legitimacy of rivals’ candidacies — for no reason — is a desperation move.