WASHINGTON – The shaky faade of party unity that the Trump campaign has sought to construct at the Republican National Convention in Cleveland endured a stiff test Wednesday night when it risked the appearance of defeated and bitter rival Sen. Ted Cruz as an invited speaker.

Cruz took the stage without having endorsed Donald Trump’s already achieved presidential nomination. To the shock and anger of many convention delegates, he pointedly declined throughout his speech in what came off as a petty display of guerrilla-like resistance.

The crowd finally erupted in booing and chants of “Endorse Trump!” as Cruz smirked and sarcastically offered, “I appreciate the enthusiasm of the New York delegation.”

This extraordinary act of conspicuous defiance laid bare the depth of the division that continues to imperil not only the Trump candidacy but the prospect for the survival of the party itself after the November election, if Trump should lose.

Cruz’s intentionally boorish behavior marred an otherwise effective convention course correction in which vice-presidential nominee Gov. Mike Pence of Indiana warmed the audience with a strong and appealing support of Trump that augured well for his role in the fall campaign.

Former House Speaker Newt Gingrich pitched in with a crowd-pleasing assurance that Trump would launch a much tougher fight against Islamic State terrorism, whose emergence he laid at the feet of President Obama and Democratic presumptive nominee Hillary Clinton.

Together, the Pence and Gingrich speeches aroused a previously uncertain convention hall, in contrast to the earlier gaffes that shook Republican confidence in the Trump campaign’s ability to conduct a professional operation in pursuit of the presidency in the fall.

On the opening day of the convention, the Trump campaign squelched an expected delegate rebellion. But it had to be done with brass-knuckle tactics, when it could have been achieved by allowing the opposing faction a face-saving floor vote.

The supposed efforts of new campaign manager Paul Manafort, an old Nixon retread, to coax Trump into being a gentler, humbler candidate fell short. When, after accepting Pence, a standard-issue party conservative, as his running mate, Trump made a mess of the Pence rollout.

He used most of it to offer a rerun of his own, often insulting primary campaign annihilation of 16 cream-puff challengers. After introducing Pence, he walked off to leave him to pay homage to the nominee with whom he has glaring political differences. Pence after all had endorsed Cruz over Trump in the Hoosier primary.

Going into the convention, Trump’s inexperience in political life had already raised widespread doubt in the public and the news media about his readiness to run the country. Rather than addressing those doubts, for two days he offered the nation’s television viewers a convention that appeared to be going off the rails.

In a major glitch, his glamorous wife, Melania, was rolled out to polish his image and instead was victimized by shoddy staff work. Another day was squandered by the discovery of unmistakable plagiarism in her speech of remarks by Michelle Obama in her own convention speech in 2008. Manafort at first dissembled rather than owning up to the charge and moving on.

Finally, on Wednesday, a speechwriter aide to Melania came forward – or was pressured – to say she had failed to recognize Michelle’s language in a speech draft given to her, and she offered to resign. She said Donald Trump rejected the offer, but nevertheless the aide was left to take the heat. It was amateur hour all over again, raising the question of how ready Trump and his campaign were for prime time.

Through these mishaps, the Trump campaign offered little detail on what he would bring to the presidency, instead largely falling back on Republican animosity toward Hillary Clinton to arouse the convention.

But Wednesday night, with Cruz’s crass and insulting non-endorsement of Trump and the strong and evocative speeches of Pence and Gingrich, plus a rousing boost from Trump younger son, Eric, the conventioneers awoke and set a more enthusiastic stage for his own acceptance speech on the closing night.