It's hard to overstate how central large campaign rallies are to President Trump's political strategy.

In 2016, his packed rallies during the primaries hinted at the solidity of his support — support that helped him secure enough of the early primary vote to make him the party front-runner. During the general election, he and his allies insisted that the rallies reflected a groundswell of support that wasn’t captured by polling. That wasn’t really the case, given that polling broadly predicted the election’s outcome. It was the case, though, that Trump voters showed sufficient enthusiasm relative to Hillary Clinton to hand him enough narrow victories that he won the electoral college vote.

This year, he faces similar head winds: low support in the polls and a consistently low favorability rating. But Trump nonetheless insists that there’s a “silent majority” supporting his reelection, one not manifested in any actual metric. To demonstrate that support, he hoped to turn again to crowded arenas and adoring fans.

The coronavirus pandemic made that tricky, postponing any rallies for several months. So Trump pushed for quick return to normal, selecting a rally at the BOK Center in Tulsa as the point at which he could jump back into the campaign with a large splash.

And, in short order, he set himself up for disaster.

Political campaigns always want to show enthusiasm, of course. It's important to any candidate that voters see them as viable, that they can establish some sense of energy and excitement. It's contagious. So what campaigns normally do is carefully manage expectations so that they can exceed them.

If a campaign is expecting 1,000 people, it will claim that it’s expecting 500. It will reserve an event space that holds 800 people. It will put out enough seats that, shortly before the event begins, organizers have to put out more — explaining loudly enough for nearby reporters to hear about how the rush of interest made them change their plans. Everything is focused on underestimating what’s expected, which has the happy side effect of making it easier to clean up the mess should 1,000 people not show up.

This is not what Trump’s campaign did before Tulsa. It repeatedly hyped the number of tickets that had been requested, even though it and anyone familiar with the ticket requesting process knew that was inflated.

On June 12, campaign manager Brad Parscale — whose background is digital marketing and not campaigning — touted 200,000 requests. Later that day: 300,000. By June 14, 800,000. On the morning of June 15, five days before the rally itself, Trump claimed that nearly a million tickets had been requested. Less than two hours later, Parscale put it at over 1 million.

That was where things sat. Politico reported that the eventual total numbered 1.1 million — suggesting either that requests slowed down or, worse, that Trump and Parscale were actively inflating a number that they knew didn't actually reflect what attendance would look like.

Politico’s report suggests that the campaign actually figured about 60,000 people would attend. The campaign built an outdoor stage, where Trump and Vice President Pence were both expected to speak. Even late on June 19, Parscale was hyping the outdoor overflow space.

“If you come to the rally and don’t get into the BOK Center before it’s full,” he tweeted, “you can still see the President in person!”

It was never full. The Tulsa Fire Department estimated that a bit over 6,000 people were there to hear Trump speak.

Why break such a fundamental rule of campaigning? A few reasons seem likely.

The first is that Trump clearly expected a better turnout. He and his campaign team had been focused on disparaging former vice president Joe Biden, his likely general election opponent, as unpopular and dull.

“We have enthusiasm like they have never seen before, actually,” Trump said during a conversation with his friend Sean Hannity last week. “And Joe has the lowest, I hear, enthusiasm on record.”

Those 6,000 people did, in fact, constitute more turnout than Biden has seen. Had the campaign set expectations that 5,000 people would show up mid-pandemic, the conversation today would be quite different. But it didn’t.

Another reason, of course, is that Trump was eager for good news in a bad week. A number of polls over the past few weeks showed Trump trailing Biden badly. His handling of the pandemic was under new scrutiny as cases spiked in several states — including Texas and Florida, which had been hyped as good examples of balancing reopening with containment. Trump’s response to a series of protests focused on the treatment of black Americans at the hands of police put his campaign’s efforts to appeal to black voters in conflict with Trump’s insistence on standing with law enforcement to appeal to his base.

So those hundreds of thousands of requested tickets were a bit of immediate good news, little dopamine rushes that could be shared with Trump and with his supporters as indicators that everything was on track as expected: Think Trump’s reeling? These 800,000 ticket requests say different.

As it became apparent that those ticket requests wouldn't even result in one-one-hundredth of that turnout, the campaign tried to spin what happened. Parscale in particular insisted that it was the fault of protesters, pointing to a temporary closure of one entry point as a security precaution as a central factor in the decline in turnout. But The Post's Dave Weigel was on the ground in Tulsa and reported that campaign staff had earlier mocked the failure of protesters to make themselves known at the rally.

The campaign also shifted metrics, hyping the millions it said had tuned in to live streams to watch Trump’s speech. This, remarkably, was the same argument that then-White House press secretary Sean Spicer used on Jan. 21, 2017, to explain why Trump’s was the most-watched inauguration in history: Sure, not as many people attended as had attended Barack Obama’s inauguration, but that doesn’t count people watching online!

The current press secretary, Kayleigh McEnany, appeared on Fox News on Monday morning, insisting that Trump wasn't even mad about the low turnout.

“The president was quite energized,” she claimed. “I was with him after the rally. It was a huge success.”

Not even a host of “Fox & Friends” bought that spin.

“We’ve known Donald Trump — he was on this show every Monday for years,” host Steve Doocy said. “That guy, who used to be on our show, would have been furious that something went haywire.”

That’s almost certainly true. It’s also true that the failure to meet expectations was a function of the expectations Trump himself set.