Former Vice President Mike Pence filed paperwork to declare his candidacy for president on June 5, 2023 – placing him in unusual ranks.

While 18 of the 49 former vice presidents have gone on to run for president, it’s rare for vice presidents to run against their former bosses. Six of these former vice presidents, including President Joe Biden, were ultimately elected president.

Pence, alongside other candidates, is expected to officially announce his bid on June 7.

Pence and former President Donald Trump have had a complicated relationship. Pence’s devout conservative evangelical Christianity was a crucial ingredient in helping carry Trump to victory in 2016.

But Trump blames Pence for the Jan. 6, 2021, Capitol riots and has said he is angry with him for certifying the 2020 election results. Pence remained trapped at the Capitol during the attack, which Trump did nothing to try to end.

There are only a few other times in American history that are vaguely similar to the unfolding battle over who will become the Republican presidential nominee. Both were extraordinarily bitter, and centuries later, their strife still makes historians and experts on the presidency – including myself – raise eyebrows.

Name-calling in 1800

There is one other time in history when a vice president ran against the president he served with in office.

In the election of 1800, Vice President Thomas Jefferson challenged incumbent President John Adams. Adams had won the presidency in 1796, and Jefferson was runner-up, making him vice president. Until 1804, the person who came in first in a presidential election became commander in chief, while the person who brought in the second-most votes became vice president.

Jefferson, though, wanted the top job.

And so when Adams ran for reelection, Jefferson ran against him in one of the most notorious races in American history.

Jefferson’s allies called Adams “a hideous hermaphroditical character which has neither the force and firmness of a man, nor the gentleness and sensibility of a woman.”

An Adams ally with the pseudonym of Burleigh, meanwhile, offered an omen if Jefferson won the presidency: “Murder, robbery, rape, adultery, and incest will be openly taught and practiced, the air will be rent with the cries of the distressed, the soil will be soaked with blood, and the nation black with crimes,” Burleigh wrote.

The two used proxies to level vicious personal attacks against one another in the press. But neither one gained the advantage. The election ended in an Electoral College tie. This set up what is sometimes known as the Revolution of 1800 – the very first time one group in political power peacefully ceded that power to another group, based on the results of an election.

Jefferson emerged victorious from the election.

‘Dumber than a guinea pig’ in 1912

But there is another point in history that is similar to the Trump vs. Pence race that is about to get underway.

Vice President Theodore Roosevelt assumed the presidency after the death of President William McKinley in 1901. Roosevelt was reelected in 1904 and decided to leave office in 1909, rather than seek another term.

Roosevelt endorsed William Howard Taft, his secretary of war, for president. And Taft won the race easily.

But Roosevelt grew unhappy with the Taft administration, as he felt it was not upholding his beliefs that the president should do what is necessary for the good of the country, as long as it is not explicitly forbidden by law.

In one instance, the Taft administration filed a lawsuit against U.S. Steel Corporation for violating antitrust laws that prevent unlawful mergers or other business practices.

Roosevelt went into a fury. Other factors were at play, but he had personally approved the steel company’s trust and viewed Taft’s actions as a personal attack against himself and his administration’s legacy.

Roosevelt challenged Taft for the Republican nomination and ran against him in 1912. The former president dusted off his bully pulpit and used his rhetorical knives to their maximum advantage against Taft.

In the spring of 1912, Roosevelt referred to Taft as a “fathead,” “puzzlewit” and “dumber than a guinea pig.”

Taft then used the term puzzlewit in a humorous, self-deprecating way to draw attention to what he felt were failures of Roosevelt. This included Roosevelt’s opposition to treaties with Great Britain and France.

Taft also said in a 1912 campaign speech in Ohio that, “I hold that the man is a demagogue and a flatterer who comes out and tells the people that they know it all. I hate a flatterer. I like a man to tell the truth straight out, and I hate to see a man try to honeyfuggle the people by telling them something he doesn’t believe.”

The 1912 Chicago Republican Convention, where the two faced off, was one of the most raucous in history. Taft and Roosevelt supporters even got into into fistfights.

The Republican Party leadership ultimately backed Taft. And Roosevelt, in dramatic fashion, removed his supporters from the convention after a speech, in which he declared, “… we stand at Armageddon, and we battle for the Lord!”

Then, Roosevelt formed the Progressive Party and split Republicans, paving the way for Democrat Woodrow Wilson’s presidential win.

No other time exactly like it

Pence’s decision to run against Trump has no direct equivalent in American history.

This election cycle will break new ground and help establish future expected norms – in part because Trump is the only candidate to have run while facing a criminal indictment and multiple other ongoing investigations of potential criminal activity.

However, if the past is a prologue, the Republican primary season will likely have more in common with the Roosevelt and Taft match-up than others, at least in terms of direct insults and attacks upon leadership style – things Trump is known for doing.

Shannon Bow O'Brien does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.