WASHINGTON — The Republican National Convention in Cleveland two weeks away looms as an opportunity for Donald Trump to reverse his slipping fortunes. Either that or it may be a formidable new hazard on his path to the presidency.

It all depends on which Donald Trump shows up. If he turns out to be the new Donald of smoother edges promised earlier by his new top strategist, Paul Manafort, following a script off a teleprompter, that would be one thing.

But if the Donald in the spotlight proves to be the same free-wheeling barn-burner continuing his take-no-prisoners assault, that would distinctly be another matter. The evidence so far has not suggested much transformation, as Trump insists that the style of the old Donald has worked just fine so far

His previously demonstrated contempt for the buttoned-down Republican Party leadership and apparatus, as represented by conciliatory GOP National Chairman Reince Priebus, so far signals Trump’s determination to march to his own drummer.

His recent declaration that he could win the White House with or without the Republican National Committee, and that he didn’t much care which it would be, wasn’t encouraging. It didn’t do much to ameliorate his relations with the party establishment he so distinctly disposed of in the primaries.

The so-called Bush family dynasty was left by the roadside with the broken-down Jeb Bush tin lizzie, along with Mitt Romney, John McCain and other recipients of his contempt and abuse.

All Trump has, as Huey Long might put it, is the people, who will flock to Cleveland as delegates pledged to him. In their anger at the status quo, they’re not likely to be talked off the meat wagon of Trump’s undefined vision of an America made great again.

So the big question is whether the Trump who shows up in Cleveland will be the same egomaniacal Donald who continues to serve up the raw meat that got him there, or the supposedly refashioned candidate of substance, reason and good will, turning the page to a more conventional bid for broader public acceptability.

Even to entertain that possibility is to invite a major horse laugh. The temptation to a man like Donald Trump, to seize the stage of an American national political campaign and pull out all the stops, will be irresistible.

Trump has already told the Republican National Committee he wants to turn the Cleveland convention into a “showbiz” extravaganza of sports stars, addressing the multitudes in the arena where LeBron James and the Cleveland Cavaliers only last month dramatically captured the pro basketball championship.

Trump, according to the Washington Post, said, “It’s very important to put some showbiz into a convention, otherwise people are going to fall asleep.” Disparaging the RNC staff, he added: “We don’t have the people who know how to put showbiz into a convention.”

For most presidential nominees of both major parties in the past, the national convention has been regarded a special opportunity to put the party’s best foot forward, in terms of its standard-bearer, its political principles, agenda and most of all solid party unity.

But having a flashy sports veneer isn’t likely to paper over the severe split in today’s Republican ranks led by the combustible force known as Donald Trump. The potential for the convention turning into a factious pep rally for him, devoid of much of the old GOP inspiration themes of Lincoln, Eisenhower and Reagan, seems a better bet.

House Speaker Paul Ryan, as the convention chairman, will have his hands full generating a true sense of celebration out of the witch’s brew he’s being left with after this year’s bizarre and divisive sorting out of presidential prospects. Ryan knows he’s now fronting for a glorified snake-oil salesman, which no doubt makes him wonder anew what he’s gotten himself into, in taking the speakership he never wanted in the first place.

Jules Witcover’s latest book is “The American Vice Presidency: From Irrelevance to Power,” published by Smithsonian Books. You can respond to this column at juleswitcover@comcast.net.

Photo: Republican U.S. presidential candidate Donald Trump speaks during a campaign rally at the Treasure Island Hotel & Casino in Las Vegas, Nevada June 18, 2016.   REUTERS/David Becker/Files