This year’s Republican convention appears to be primed for a rupture of a kind we haven’t seen since Teddy Roosevelt broke dramatically with the party in 1912. The parallels are striking: The party is riven between establishment and insurgents. The people’s choice is prone to intemperate remarks and hotheaded declarations—to the delight of his followers and the frustration of party leaders. And, as Roosevelt did, this year’s front-runner claims he’s being screwed by the establishment—even having delegates stolen—and is vowing to do something about it. Donald Trump has openly flirted with the idea of running as a third-party candidate, and on Tuesday he even took back his pledge to support the GOP nominee if he’s not chosen. “[If] I go,” he warned earlier this month, “I will tell you, these millions of people that joined, they’re all coming with me.”

But if history is any guide, even a Trump exodus may be less consequential than many are imagining.

Running as a third-party candidate, TR certainly put up a strong fight, placing second overall. But, beyond that, his eventual decision to run on a third-party ticket had few lasting effects. It didn’t radically change the character of the GOP. It didn’t even present its members with a credible alternative beyond 1912. Like many third parties in American history, the Progressive Party that Roosevelt created was held together primarily by its adherents’ love for its standard-bearer. And that cult of personality wasn’t enough to make up for the history, infrastructure and deep bench of talented leaders that his movement lacked. 

At the time, the high drama of the situation suggested that it might turn out otherwise. On Saturday, June 15, 1912, two days before the Republican National Convention was to begin, Theodore Roosevelt, the former and would-be president, pulled into Chicago’s La Salle Station. Despite the late-afternoon summer heat and humidity, huge crowds spilled into the railroad yards. Cheerfully flapping his cowboy hat, Roosevelt rode to the Congress Hotel on Michigan Avenue, several blocks east. Brass bands blared and diehard supporters jogged alongside his car. When his legions remained massed in Grant Park across the street, TR spoke from his hotel room balcony, vowing that William Howard Taft—the incumbent president and TR’s rival for the nomination—wouldn’t get away with stealing delegates (some 72 were in dispute). Two days later, in a formal speech, he said much the same thing, warning that if the delegates weren’t fairly tallied, Republicans shouldn’t feel bound to support the convention’s choice. “We stand at Armageddon,” he bombastically declared, “and we battle for the Lord!” By the time the convention was over, Roosevelt—rebuffed by the party establishment—resolved to form a new political party of his own. 

One can imagine a similar scene unfolding at the GOP convention this summer in Cleveland. This year’s struggle, however, may also prove to be long on theatrics but short on consequence. If Trump is denied the nomination and runs as an independent—or even if the #NeverTrump crowd loses and mounts its own third-party run—the GOP will more likely than not remain the same uncomfortable alliance of business conservatives and right-wing cultural populists that it has been, more or less, since the time of Richard Nixon. Whether in 1912 or 2016, one man, no matter how charismatic, strong-willed, or iconoclastic, cannot invent or remake a political party. ...