As Republicans gather in Cleveland this week, celebrity businessman and provocateur Donald Trump has within his grasp a long-sought goal: his party's nomination for president. That is an incredible, impossible state of affairs for some — including a number of Republicans who remain in disbelief that a broad field of tested conservatives and elected officials was bested by a brash, elbows-out billionaire sporting a "Make America Great Again" feed cap and a bumper-sticker ideology.

Trump's central task in the coming week will be to knit together a party that is more fractured heading into its convention kickoff than at any time in recent history. While Democrats witnessed Sen. Bernie Sanders finally offering his endorsement of Hillary Clinton last week, "Never Trump" forces were scrambling to subvert their party's presumptive nominee. Seemingly unfamiliar with the notion of the olive branch, Trump on Friday bragged that he had vanquished the rogue group. "Never Trump is never more," he tweeted. "They were crushed last night in Cleveland at Rules Committee." One hardly need spell out the consequences should he one day bring such swagger to global affairs.

Throughout his campaign, Trump has been so light on policy and philosophy that he has sparked doubts among party faithful about his devotion to Republican principles. Perhaps to compensate, the party has produced a platform so conservative that it will be difficult for it to reach beyond a narrowing base. The platform declares pornography a "public health crisis," considers coal to be clean energy and stipulates that laws "must be consistent with God-given, natural rights." It calls for the Bible to be taught in public schools and for a constitutional amendment to overturn the high-court ruling that legalized same-sex marriage. In one of its most troubling planks, the party of Lincoln now calls specifically for a physical wall to be built along the country's southern border.

It's clear now that the more presidential style Trump once hinted he would soon unveil is not coming. His is a brash, bullying demeanor that relishes bare-fisted exchanges of insults and has alienated not just most Democrats, but a number of high-ranking Republicans. Many plan to skip the convention, some on the flimsiest of pretexts. Sen. Jeff Flake, of Arizona, literally said he had to mow his lawn. Sen. John McCain will be somewhere over the Grand Canyon. Sarah Palin won't be able to make it in from Alaska.

One suspects Trump would just as soon they and their establishment taint stayed away. His convention will feature an eclectic mix: the black prosperity gospel preacher intent on converting Sanders — who is Jewish — to Christianity; the Hispanic actor who wants President Obama arrested and sent to Guantanamo; basketball coach Bobby Knight, who once choked one of his own players in a fit of rage; and, for good measure, the chief lobbyist for the NRA. Throw in a few elected officials, Las Vegas casino owner Phil Ruffin and you have a spectacle worthy of Trump's old reality TV show.

For all of the gamesmanship, politics is serious business with serious consequences. Trump, it must be admitted, has demonstrated a knack for tapping into the frustrations and yearnings for strong leadership within a significant segment of the electorate that many others had underestimated. Still, the Republican Party is about to make a leap of faith with a candidate who has yet to show the measured temperament and steady hand needed to guide a superpower whose actions (and hesitations) can affect the fate of the world.

Perhaps Trump's selection of low-key Indiana Gov. Mike Pence, who served a decade in the House, indicates Trump is more seriously considering the challenge at hand. This Editorial Board hopes so. Conventions are a time for candidates to frame themselves as future presidents, ready on Day One. So far, Trump has eschewed the statesman model. But in the wake of the blood-soaked tragedy in Nice, France, and the power struggle in Turkey, Trump should at least be prepared to show that he can be patient as well as strong, and willing to look at facts before plunging ahead. If the party must have Trump, cooler Republican heads must set aside their differences and engage quickly to school Trump in the weighty complexities of the office he seeks.

It is also to be hoped that next week's events are not so over-the-top that they spark the kind of protests that endanger everyone. Cleveland is beefing up its security in advance of the 50,000 visitors expected. But its department is still under federal oversight enacted after a Justice Department finding of a pattern of excessive force following the shooting death of 12-year-old Tamir Rice. Ohio also has open-carry laws that will allow many at the convention to carry firearms, although not in the convention hall itself. That is a volatile mix for a nation that finds itself at a flash point in race relations, particularly as regards law enforcement.