After months in which Donald Trump practically begged President Joe Biden to debate him, the Democratic incumbent opened the door a few weeks ago. “I am, somewhere, I don’t know when, but I am happy to debate him,” Biden told radio host Howard Stern.

Evidently, he meant it. My MSNBC colleague Clarissa-Jan Lim noted this morning:

President Joe Biden and presumptive GOP nominee Donald Trump will face off on June 27, after a public back-and-forth on Wednesday morning that culminated in both candidates agreeing to a CNN invitation for a debate. The debate will be held at 9 p.m. ET at the network’s studios in Atlanta. CNN said there will be no audience at the debate, fulfilling a key demand from Biden’s camp.

There are plenty of additional details that will need to be worked out — we don’t yet know who the moderators will be, for example — but a plan for the election season is apparently taking shape. The presumptive nominees from both parties are prepared to forgo the Commission on Presidential Debate’s schedule and arrange their own events.

As things stand, the first debate will be held on CNN on June 27, followed by a second debate on ABC on September 10. The plan also apparently includes a vice presidential debate in July.

Biden got the ball rolling on this in a rather pointed social media message published online this morning.

Trump, relying on his own online platform, responded soon after, “Just tell me when, I’ll be there.”

But that’s not all he said. In the same missive, the Republican added that Biden is “the WORST debater I have ever faced — He can’t put two sentences together!”

I’m going to assume that someone close to the former president has told him about how best to play the expectations game, but he doesn’t appear to have understood the lesson.

As we discuss every four years around this time, presidential campaigns invest quite a bit of energy in trying to manage expectations ahead of the debates. Aides sometimes go to comical lengths to argue that their rival is an extraordinary debater, while their boss is woefully unprepared for the events.

My personal favorite came in 2004, when the Bush/Cheney team, with great sincerity, told campaign reporters that John Kerry was the greatest debater since Cicero, the legendary orator from ancient Rome.

There’s no great mystery surrounding the strategy: The higher the expectations, the harder it is for a candidate to meet them. Similarly, candidates facing low expectations can claim a “victory” simply by avoiding dramatic mistakes.

Four years ago, Trump — whom no one has ever accused of being a tactical mastermind — got all of this backwards, telling the public that he would “DESTROY” Biden in the debates. In fact, the GOP incumbent spent months telling the public that Biden was an addled old man, hiding in his basement, unable to speak in complete sentences.

The results were predictable: National polling found that a plurality of Americans expected Trump to win his 2020 debates against Biden. The Republican set out to convince the public that he would bulldoze his Democratic challenger, and many voters believed him.

But the plan backfired: When Biden and Trump actually met for their debates, post-event polling found that most Americans thought Biden won, thanks in part to the low expectations he was easily able to clear.

Four years later, Trump, apparently a slow learner, is making the identical mistake. The more he tells the public that Biden “can’t put two sentences together,” the easier the task for the Democratic incumbent. If Biden is lucky, the former president will stick to his current strategy, indifferent to the fact that he’s inadvertently helping the opponent he’s trying to hurt.

This post updates our related earlier coverage.