Even before Donald Trump secured the Republican nomination, the billionaire brander and reality TV star was promising that he would put on a convention spectacle unlike any that had ever come before.

The one that had nominated Mitt Romney four years ago in Tampa was “the single most boring convention I’ve ever seen,” he said in an interview with The Washington Post in April.

“It’s very important to put some showbiz into a convention. Otherwise, people are going to fall asleep,” he added. “We don’t have the people who know how to put showbiz into a convention.”

There have been arresting moments.

One was his professional-wrestling-style entrance on the convention stage Monday night, illuminated in silhouette as the loudspeakers blared Queen’s “We Are the Champions.” Just being there on the first day of the convention, rather than following the tradition of staying away until Thursday night’s acceptance speech, showed how Trump is infusing the four-day event with a larger-than-usual presence.

Former Republican presidential candidate Ted Cruz can't seem to escape Donald Trump. At a rally in Cleveland, Ohio, Cruz was interrupted by Trump's plane as it flew overhead just as he was telling supporters, “our party now has a nominee.” (Reuters)

On Wednesday, Trump returned to Cleveland, descending from the sky onto the lawn of the Great Lakes Science Center in the now-famous helicopter that bears his name. It was a reprise of a spectacle that had dazzled voters at the Iowa State Fair.

But the Trump Show has yet to dazzle — and there have been some moments where it has been almost painful to watch.

Every convention has its hits and misses. But rarely has a presidential candidate cared so personally about pizzazz.

Trump’s campaign team has long boasted of his showman’s flair and attention to the small but telling details of stagecraft.

Aides say Trump is deeply involved in the creation of his ads and selects which music will play when he walks onstage at his rallies and which will play when he walks off. He is particular about what type of microphone is on the stage.

Campaign spokeswoman Hope Hicks said that Trump personally designed the MAKE AMERICA GREAT AGAIN caps that have become his campaign’s signature apparel.

“He came up with that. He said, ‘Bring me this style hat. I want our logo on it. This is how I want it to look,” Hicks said. “He was involved in everything. He picked the stitching, the colors.”

At the Republican National Convention in Cleveland, vendors are selling everything from “Hillary for Prison” T-shirts to Donald Trump whoopee cushions. (Jorge Ribas/The Washington Post)

But there have been times when it has been difficult to tell whether anyone was stage-managing the convention. Or even doing the kind of due diligence that might have prevented Trump’s wife Melania from delivering a speech that had been plagiarized from one given at the 2008 Democratic convention by now-first lady Michelle Obama.

Its first night, for instance, ended in a fizzle. Sen. Joni Ernst (R-Iowa) is considered a rising star of her party, sure to excite the base. But she got a speaking slot at the end, long after most of the seats in the Quicken Loans Arena had emptied.

The figures from sports and entertainment who have shown up on the stage have largely been B-listers. None of them have approached the celebrity status of actor-director Clint Eastwood, who headlined Romney’s convention, albeit in a bizarre appearance where he spoke to a chair.

Each evening has ostensibly had a theme. Monday was “Make America Safe Again;” Tuesday was “Make America Work Again;” Wednesday was “Make America First Again,” and Thursday is set to be “Make America One Again.”

But few of the speakers seem to be bound by those slogans. Tuesday, for instance, most of them focused on making the argument that Democratic nominee-in-waiting Hillary Clinton should be in prison, not on spelling out how Trump would revive the economy and bring back jobs.

Some of Trump’s out-of-the-box ideas, meanwhile, never came to fruition.

During a June 16 rally at a honky-tonk in Dallas, Trump announced that he wanted to host a “winners’ night” during the convention that would feature all of the “champions” who have endorsed him.

“We’re going to have a great convention in Cleveland, and we are going to, I think, have a winners night so instead of politicians, we’re going to have some of these great people,” Trump said. “We have such unbelievable endorsements. So, maybe, I haven’t even asked him yet, but you take a Bobby Knight and you take some of these great winners — they’re winners, there aren’t many winners — you take these winners, and we’re going to have them speak.”

“That,” he added, “will probably be the best-attended night of the whole deal. So we’re going to do that.”

So far, however, there has been no sign of Knight, the famed Indiana basketball coach.

The name of another sports celebrity, quarterback Tim Tebow, showed up on an early roster for Thursday night. That prompted Tebow to post a video in which he denied it, saying: “It’s amazing how fast rumors fly, and that’s exactly what it is — a rumor.”

Meanwhile, the actual speakers to take the stage have included plenty of party elders and semi-obscure officeholders.

Trump has discovered that it is hard to make something called a convention anything but . . . conventional.