POLITICO on the potential spoiler effect of this third-party candidacy. The story observes: “Democrats feel that the Green Party’s Jill Stein siphoned votes from Hillary Clinton in 2016, helping usher former President Donald Trump into office.” But, as my book Presidential Elections and Majority Rule analyzed, Gary Johnson running as the Libertarian candidate was a more significant third-party candidate in 2016 than even Jill Stein. Whether Clinton would have beaten Trump in a two-candidate runoff, or in an instant runoff using ranked-choice ballots, would have depended ultimately on what Gary Johnson’s voters in the key battleground states of Michigan, Pennsylvania, and Wisconsin would have done.

It is also worth noting, as Jonathan Cervas and Bernie Grofman extensively studied, that in 2020 the Libertarian candidate Jo Jorgensen’s vote share was larger than Biden’s margin of victory in several key states and “probably cost Donald Trump victory in at least two states: Arizona and Georgia.” Based on their findings, their article is pointedly titled “Why Donald Trump Should Be a Fervent Advocate of Using Ranked-Choice Voting in 2024.”

Whether third-party “spoilers” hurt Democrats (like Al Gore in 2000) or Republicans (like George H. W. Bush in 1992), the capacity of presidential candidates to win all of a state’s electoral votes without winning a majority of the state’s popular vote is one of the most irrational features of our entire presidential election system and, as my book showed, inconsistent with the original intent and understanding of how the Twelfth Amendment’s reconfiguration of the Electoral College process was supposed to operate.

This defect has been hugely consequential at several key points in US history, most notably causing James Polk’s victory over Henry Clay in 1844, which destabilized the Missouri Compromise and set the nation on the road to the Civil War. Likewise, the fracturing of the Republican vote between Roosevelt and Taft in 1912, causing Wilson to prevail with little over 40% of the popular vote nationally, affected how the US handled World War I and thus, according to some historians, the draconian peace terms against Germany in the aftermath of that war that set the stage for the rise of Hitler and all the horrific ensuing consequences.

One need not speculate about long-term historical effects to recognize the acute danger that an ideologically “purist” third-party candidate can cause in plurality-winner electoral system. That was the situation in 1844. Henry Clay was running on a platform that opposed the expansion of slavery, while Polk was the candidate of “Manifest Destiny” and westward expansion–including taking territory from Mexico through war–in order to add slave states to the Union. To the left of Clay was James Birney, the nominee of the abolitionist Liberty party, which did not view Clay was anti-slavery enough. Birney’s votes in New York cost Clay that state and, with it, the presidency. Abraham Lincoln was one of many Clay’s supporters who lamented at the time the ideological purity of Birney’s anti-slavery voters who caused the election of pro-slavery Polk. “If the Whig abolitionists in New York had voted with us last fall, Mr. Clay would now be President,” Lincoln wrote in October 1845, adding that “[I]f the fruit of electing Mr. Clay would have been to prevent the extension of slavery,” it could not have been “evil” for abolitionists to support Clay over Birney in order to defeat Polk. (See page 71 of Presidential Elections and Majority Rule.)

The solution to this problem is for states to require presidential candidates to win a majority of the state’s popular vote in order to receive all of the state’s electoral votes. This solution can be implemented either through ranked-choice voting (my preference) or a conventional two-stage voting system (which could have a subsequent runoff or instead a California-style preliminary round of voting leading to only two candidates on the November general election ballot). It is likely too late as a practical matter, unfortunately, for any of these solutions to adopted in states before the November 2024 election. Therefore, for the sake of the nation, one hopes that 2024 avoids becoming a repeat of what happened in 1844 (among other times).