Donald Trump cheered the entrance of Robert F. Kennedy Jr. into the 2024 election as "good for MAGA," while Democrats criticized RFK Jr.’s ambitions for being a spoiler and possibly throwing the race to Trump.
But will RFK Jr. hurt Trump or Biden more?
To find an answer, I’ll analyze the presidential elections throughout history when there was a viable third party.
My research reveals that when a third party or independent presidential candidate challenges the two-party system when an incumbent president is on the ballot, the incumbent president wins half the time.
Third party and independent candidates do most of their damage when there isn’t an incumbent running for reelection. The party in control of the White House loses two out of three races in these “open seat” situations.
Additional research shows that independent candidates and third parties tend to pull away votes from challengers, even when those challengers are successful. Because third parties and independents split the anti-establishment vote, challengers such as Trump should worry more about third party and independent candidates — RFK Jr. most notably — than Biden during the 2024 election.
There are four cases (George H. W. Bush, Jimmy Carter, William Howard Taft and Benjamin Harrison) where an incumbent lost after facing a credible independent or third-party challenger who garnered some minimal degree of national attention.
There are just as many cases, four, where a president faced a third party or independent, and prevailed: Bill Clinton, Harry Truman, Calvin Coolidge, and Andrew Jackson.
Independents and third parties do the most damage in races where there is not an incumbent on the ticket.
Of those nine cases, six of those helped cause the party in power to lose the White House (2016, 2000, 1968, 1860, 1852, 1848). In only three of these scenarios did the party in power maintain control of the White House — all during the years before the modern two-party system.
But there’s an additional factor both Democrats and Republicans should consider.
My prior research shows that when third parties run presidential candidates, they tend to weaken the challenger’s performance, even when the challenger manages to win.
Polling evidence shows that in 1992, independent H. Ross Perot’s temporary exit from the presidential race in July dramatically boosted Clinton’s position.
Perot’s return to the race in October cut significantly into Clinton’s lead, making Clinton’s eventual win over Bush much more narrow than it otherwise would have been.
Similar research by Steve Kornacki, writing for Salon (now with NBC/MSNBC), shows that independent presidential candidate John Anderson’s effort did not cost Carter the election — and may have cut into Reagan’s popular vote totals.
George Wallace’s independent presence in the 1968 presidential election cut deeply into Republican Richard Nixon’s electoral vote totals in the South and helped Democratic candidate Hubert Humphrey, which may have been the Alabama governor’s goal all along. Nixon certainly worried about the chance of this happening.
In conclusion, there’s no guarantee that the RFK Jr. entrance into the election will benefit Trump.
Despite Kennedy’s former association with the Democratic Party and some liberal leanings, particularly concerning the environment, his tough-on-immigrant border policies and anti-vaccine theories in particular may well appeal more to like-minded conservatives and center-right independents who can’t stomach the thought of a second Trump presidency — or another four years of Biden.
If anything, Trump may well have more to worry about than Biden, as these independents and third-party candidates have more often historically cut into a challenger’s chances at the ballot box.
John A. Tures is a professor of political science at LaGrange College in LaGrange, Ga. His views are his own. He can be reached at jtures@lagrange.edu. His X account is @JohnTures2.
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