No one has seen anything like this. Donald Trump—without past political or military experience and facing a formidable Republican field—bludgeoned 16 opponents into submission, rewrote the rule book and became the GOP’s presumptive presidential nominee.
As extraordinary as this is, Mr. Trump’s success was achieved only by inflicting tremendous damage to the party. To win the general election in November, he must now unify a GOP with a deeper divide than it has faced in more than half a century.
Mr. Trump must disabuse himself of the notion he expressed last week that he “can win without” party unity. As if to prove it, Mr. Trump—on the morning he routed Ted Cruz in Indiana—implied that Sen. Cruz’s father was involved in President John F. Kennedy’s assassination. This was nuts. Winning the presidency is difficult for Republicans under normal circumstances; Mr. Trump’s scorched-earth tactics have left deep wounds that make victory more uncertain.
To heal his party, Mr. Trump should approach the convention gingerly. He shouldn’t mess with the rules or upend the platform and must energize the GOP with his vice-presidential pick.
To continue reading Mr. Rove's column in the Wall Street Journal, click here.