In political circles, it’s long been known as the “Rose Garden strategy”: incumbent presidents using a combination of statecraft, public relations, and the power of the office to propel their stature ahead of a re-election campaign.

Donald Trump put an ugly twist on the strategy yesterday, ostensibly appearing in the White House Rose Garden to announce Chinese punishments over a crackdown in Hong Kong. As the New York Times noted, it wasn’t long before the Republican president shifted his attention to what was actually on his mind.

What followed instead was an hour of presidential stream of consciousness as Mr. Trump drifted seemingly at random from one topic to another, often in the same run-on sentence. Even for a president who rarely sticks to the script and wanders from thought to thought, it was one of the most rambling performances of his presidency.

“At times,” the article added, “it was hard to understand what he meant.”

The purpose of the gathering, for all intents and purposes, was for Trump to turn a White House event into a televised campaign rally, filled with bizarre attacks on Joe Biden. A Washington Post analysis added this morning, “[The president] invoked his opponent’s name nearly 30 times on a range of topics, and despite his claims otherwise, sounded like an underdog on shaky ground throwing spaghetti at the wall to find a new message that might stick.”

It’s an important detail. Even if we look past Trump’s jaw-dropping dishonesty — the Republican spent the event lying at an aggressive pace — and his difficulties in speaking in complete sentences, what the president inadvertently helped prove is that he still doesn’t have a coherent line of attack against his 2020 rival.

Dana Milbank helped round up the various smears Trump threw at Biden, and the collection was a garbled mess. Evidently, Americans are supposed to believe that the former vice president would, among other things, get rid of windows by 2030, abolish suburbs, and “incentivize illegal alien child smuggling.” The president added that the Delaware Democrat has gone too far to the “right.”

One assumes he meant “left,” but given Trump’s rambling, largely incoherent performance, he seemed unable to tell up from down, much less left from right.

Through much of Barack Obama’s presidency, Republicans struggled to settle on their preferred caricature. They argued that he was too tough and too weak; too smart and too dumb; too aggressive and too passive. It was never altogether clear exactly why the public was supposed to reject him.

With Biden, a similar problem is emerging. Americans have gotten to know the former vice president over the years — he’s been a prominent public figure for several decades — and his critics have had plenty of time to figure out what to say about him. But as Election Day 2020 approaches, Trump nevertheless seems lost, making up nonsense, and meandering between smears he doesn’t even seem to understand.