Conventional wisdom has it that the 2016 presidential campaign has no parallel in American history. Such wisdom would point to the first female to head a major-party ticket. It would note the first billionaire populist as a major party's presumptive nominee. There might even be a reference to the high negatives and general aroma of untrustworthiness emanating from both campaigns.

Conventionally speaking, all of this insight is entirely on the mark. But speaking of conventional things, the 2016 race might find its parallel yet, in the extraordinary presidential election of 1912.

Briefly, the circumstances were these. Theodore Roosevelt, having won election to the presidency in 1904, promised that he would not seek re-election in 1908. No one, he thought, should hold the office longer than George Washington's eight years. And by 1908 Roosevelt would have been president for nearly that long, having succeeded to the office from the vice presidency upon President William McKinley's assassination in 1901.

By 1908, Roosevelt had come to regret his pledge, but he kept it.

Fast-forward to 1912. By then Roosevelt had come to regret something else, namely his decision to anoint William Howard Taft as his preferred successor. Convinced that Taft as president was insufficiently progressive, Roosevelt returned from a nearly yearlong African safari to eventually make another decision: He would challenge Taft for the Republican nomination in 1912.

The heart of that challenge was the then-infant primary election process. Roosevelt won most of the state primaries, but there weren't enough of them at the time to make a difference. Taft forces controlled the party machinery and the convention, including what were the "superdelegates" of that era — and the nomination was his.

TR now had another decision to make. Managing (without great difficulty) to convince himself that the convention had been rigged against him, he decided to organize a third party. Under the banner of the suddenly formed Progressive Party, Roosevelt took to the fall campaign against Taft, Democratic candidate Woodrow Wilson and Socialist Party standard-bearer Eugene Debs.

Wilson, of course, was victorious. In truth, TR undertook his crusade convinced that this would be the result. Nonetheless, he decided that it was important to fight the good fight for his version of progressivism anyway. Dividing the Republican Party — and costing his party the White House in the process — was worth it. Or so TR surmised.

Are you starting to sniff the parallel? To be sure, no historical analogy is perfect. More than that, no one knows what's going to happen in Cleveland at the Republican National Convention. But the potential for a compelling story and a near-historic echo is certainly there. And it's there in not just one, but two, potential ways.

An obvious difference is that today what's at stake is the future of conservatism, not progressivism, within the Republican Party. That stipulated, let's continue — and speculate.

Will Donald Trump continue to be Donald Trump — to shoot from the hip? Will he so alienate the party establishment, not to mention this and that voting bloc, that the GOP establishment will promote a convention rules change (say, a two-thirds requirement for endorsement) that will deny Trump the nomination? If so, Trump might well walk out and organize his own third party.

Or will the convention go ahead and nominate Trump, even though Trump cannot help but be Trump? In that case, right-of-center Republicans might well choose to pull their own version of TR in 1912 and organize a third-party effort designed to save conservatism and deny Trump the presidency. They might even choose to do so, knowing what TR knew in 1912, namely that their candidate would not win.

In 2016, there will be no former president jumping into the race to reclaim what he feels is rightfully his. But otherwise the parallel is pretty powerful. Before the 1912 convention, no one, including TR, anticipated what was going to happen after that gathering. And today? No one (and "no one" includes Donald Trump, party chair Reince Priebus, Speaker Paul Ryan and 2012 candidate Mitt Romney) knows what's going to take place in Cleveland, much less afterward.

But what could happen is clear. A larger-than-life figure (Trump as TR) could feel aggrieved, even (this time) justifiably aggrieved, and impulsively take to the field at the head of a insurgent effort — and lose. Or Republican conservatives (as opposed to 1912-era Republican progressives) could feel aggrieved, undertake a quixotic TR-style campaign and sink the GOP in the process.

Or …

Unlike TR, those same conservatives might convince themselves that they could actually win, given the high negatives of Trump and Hillary Clinton. Roosevelt's single hope in 1912 was that the Democrats would nominate their more conservative alternative, "Champ" Clark of Missouri, and not Wilson. But after many ballots, given the two-thirds threshold then required by the Democrats, Wilson prevailed, and the rest is history. He was, after all, a progressive and a fresh face.

A conservative and a fresh face might well have been successful in 2016. But at the moment both Trump and Clinton stand in the way. Whether the story will take any further turns — with or without parallel — remains very much up in the air.

John C. "Chuck" Chalberg is a retired history professor and senior fellow at the Center of the American Experiment and performs as Theodore Roosevelt. He writes from Bloomington.