Donald Trump walked on stage at the Republican National Convention July 18 to Queen's "We Are the Champions." Trump was introducing his wife Melania who also addressed the crowd. (The Washington Post)

Donald Trump has left himself with a mighty challenge for the final day of the Republican National Convention. After three days of tumult and controversy, the success — or not — of the week now depends even more heavily than it should on his performance Thursday night.

Trump might not have it any other way. Maybe this was always part of the plan, to create the drama and heighten the stakes ahead of his acceptance speech. After all, the campaign has always been about him. He’s the candidate, chief strategist, communications director and opposition researcher all wrapped up in one unlikely package. Thursday night, he must also be seen as a possible president.

The first days of his convention have been messy, highlighting a divided party and a convention floor that has seen angry protest and at other times what might be described as low energy. When the delegates have sparked to life, it has often been due to the contempt that many have for Hillary Clinton. The raw and unofficial battle cry here — “Lock her up!” — speaks to the coarseness and negativity of 2016.

No doubt Trump is confident about Thursday. By his own boasts, he is the ultimate clutch performer, the man with ice water in his veins in crucial moments. He believes, as he has said throughout the campaign, that he is a winner — capable of dominating in any setting.

Republican presidential nominee Donald Trump arrived in Cleveland, Ohio, July 20, ahead of vice-presidential pick Mike Pence's speech at the Republican National Convention. (Reuters)

What awaits him Thursday night, however, is no “Apprentice” moment. It is reality TV at the highest level — as serious and critical a test as he has faced during the 13 months he has been a candidate. He’ll be judged in ways he hasn’t been evaluated before, and likely by a larger audience than any so far.

Ratings, however, aren’t the issue. He probably will get them. He draws eyeballs, for better and for worse. But what will really count is whether Trump accomplishes everything that still needs to be done. He needs this convention to send him out of Cleveland on Thursday night absent controversy, without damaging questions trailing behind him and, in the best of all worlds, with a wider group of voters prepared to take a fresh look at him.

For Trump, this will be unlike the other tests of his candidacy, one that will cross-pressure him. The most unconventional of candidates now must navigate the most conventional rite of passage of any presidential campaign as he makes the official transition to general-election candidate and possible president.

Trump promised more than his convention has delivered. Each night has had a crisp theme: making America safe, making America work, making America first. But the speeches have not always followed the theme. Most of Tuesday’s speeches, for example, lacked real content about jobs or the economy, whether in critiquing Clinton’s policies or outlining what Trump would do.

Trump promised showbiz, glitz, glamour to spice up what can be a parade of politicians, many of them not well known to the country, delivering boilerplate rhetoric. But “pizzazz” isn’t the first word to describe the events so far. The convention has delivered little on that front that has broken through, with celebrities who are aging stars and not even as well known as some of the politicians.

The best showbiz moment came Monday night when Trump rose up silhouetted on the stage in a smoky cloud, a Las Vegas entry in the heart of the Rust Belt. On Wednesday, he flew into Cleveland and then switched to his helicopter, with the familiar Trump logo, for the short trip to a field by the lake. It was a photo-op moment, but hardly something that fulfills his promise of something really different.

Some speeches have broken through. Former New York mayor Rudolph Giuliani roused the convention delegates Monday with a fiery speech that offered validation of Trump as a law-and-order candidate who has a softer human side. New Jersey Gov. Chris Christie sent a jolt of electricity through the convention on Tuesday night when he played prosecutor against Clinton’s record. “Guilty or not guilty?” he asked. The crowd roared back its predictable verdict.

Still, many speakers have left the audience flat and the television networks scrambling for counter-programming. Ordinarily, the networks spend most of the hour between 10 and 11 p.m. with their cameras focused on the stage and the speakers. This week, because some of those speakers have lacked star power or a compelling message, the networks have cut away. Through its own scheduling decision, the campaign has robbed itself of what should be its best opportunity to deliver an undiluted message on behalf of the candidate.

The Trump family has drawn much praise. Donald Trump Jr. was effective on Tuesday night in talking about his father. Before he spoke, Tiffany Trump, the second-youngest of his five children, offered testimonials about Trump as a dad. Before Trump speaks on Thursday, the convention will also have heard from two other children, Eric and Ivanka Trump

The highlight of Monday’s program was Melania Trump. She wowed the delegates, and no doubt many watching on television with her poise and delivery. But within hours, the campaign was plunged into controversy over charges of plagiarism because of passages in the speech that had been lifted from the 2008 convention speech by Michelle Obama.

The controversy provided chum for a huge and ravenous press corps, which pursued the details of how something as basic as the vetting of such a high-profile speech had gone wrong. For a day, the campaign hunkered down, pointed fingers and tried to ride out the storm — without success.

On Wednesday, they pivoted to a different strategy by identifying a culprit. Meredith McIver, a writer who has worked on Trump’s books, came forward and confessed that the error was hers alone.

Trump must hope that the confession will end the controversy. He needs a clean break ahead of Thursday night. He wants the focus to be on him and his speech, not on mistakes made by his campaign that have added to doubts about its readiness for what will be a hard-fought contest against the Clinton machinery.

Wednesday’s series of speeches brought more coherence to a pro-Trump message, highlighted by the well-received speech from Trump’s running mate, Indiana Gov. Mike Pence. But just as the convention seemed to be pivoting toward greater harmony, Sen. Ted Cruz blew it up with a speech in which he refused again to endorse Trump. The Texan who has an eye on 2020 was booed lustily as he ended his speech. It was one more case of Trump prevailing over Cruz but an episode that nonetheless fed the subplot of a party divided.

Trump is at his best — and sometimes his worst — when he is mostly unscripted. His free-form style, in defiance of conventional rules of politics, worked during the primaries. But now he is being told he must curtail those instincts and use a text and a teleprompter. It will be an uncomfortable experience.

When he spoke to the Cleveland delegates from Trump Tower in New York, after being formally nominated on Tuesday night, he was clearly reading his brief remarks with such cadence and precision that he conveyed his distaste at being shackled to prewritten words. But can he be both freewheeling and off the cuff, and disciplined and serious?

What’s left for Trump on Thursday? Only this: He needs to energize his base. He needs to unify his party. He needs to make himself a more appealing candidate to the wider electorate. He needs to soften his image. He needs to make the case against Clinton, but more he needs to make a positive case for himself. He needs to show he has a grasp of issues and answers to problems that add heft and credibility to the slogans that have been the hallmark of his campaign.

Mostly he needs to find a way to combine the most effective theme of his candidacy — that of an outsider who connects with disgruntled and disaffected voters and will shake up Washington — with something that reassures people of his temperament, stability and reliability. He can still redeem the week, but the opening days haven’t done much to help him. As always, it’s going to be all about Donald.