The Primary Model
2024 Forecast
75% Certain Kamala Harris Will Be Elected President
Forecast Model Batting 5 for 7 Since 1996, Retroactively 25 for 28 Since 1912
The Primary Model gives the presumptive Democratic nominee Kamala Harris a 75% chance to defeat Republican Donald Trump in November. Granted Harris did not win a single vote in presidential primaries this year but the performance of President Joe Biden, whom she replaced as the head of the Democratic ticket after his withdrawal, augurs well for her success in November. The precedent for this adjustment of the Primary Model is provided by how the model algorithm has been handling two cases in which a sitting president withdrew from the presidential race during the election year. It happened in 1952 and 1968, when first Harry Truman and then Lyndon Johnson dropped out of the presidential race after primary contests were held. In both cases the model algorithm has assigned the primary performance of the departed presidents to the ultimate Democratic nominees. With that adjustment, the model gets it right, albeit retroactively, both times (1952 and 1968).
The forecast of a likely Harris victory in November takes account of the outcomes of early primaries (New Hampshire and South Carolina). While both Biden and Trump won their respective contests in those states, the margin of victory was far larger on the Democratic side. Transferring this advantage to Harris makes her the favorite in November. What also benefits Harris in the general election is the working of an electoral cycle that favors the White House party after one term. The combination of those two factors predicts a Harris victory over Trump in 2024 with 75-percent certainty. As for the Electoral College, the most likely outcome of the 2024 presidential election predicted by the model is that Harris will get 315 electoral votes and Trump 223.
The Primary Model (primarymodel.com) relies on presidential primaries and an election cycle as predictors of the vote in the general election. This year the forecast is arrived at in a three-step process: first the algorithm predicts the popular vote in 2024, then it converts that estimate into a prediction of the Electoral College vote, and finally a simulation is run to estimate the likelihood of either candidate winning the election.
The core premise of the Primary Model is that winning primaries predicts electoral victory in November. On the Democratic side, Joe Biden received 63.9 percent of the primary vote in New Hampshire, as a write-in candidate no less, followed by 96.2 percent in South Carolina. Meanwhile, on the Republican side, Donald Trump scored 54.3 percent in New Hampshire and 59.8 percent in South Carolina. Bottom line: the Democrat had the stronger primary performance. With Harris as the presumptive Democratic nominee after Biden’s withdrawal, she is now favored to be elected president.
What also boosts her prospects in 2024 is a cycle of presidential elections operating for nearly 200 years. While partisan tenure in the White House fluctuates regularly, swinging back and forth after about two to three terms on average, it is still a safe bet after one term.
Another way to illustrate this advantage is the snapshot of elections since 1960. After one term in the White House the incumbent party has won most contests unlike the situation when it has held office for two or more terms.
Presidential elections going back as far as 1912 are used to estimate the weight of primary performance. It was in 1912 that presidential primaries were introduced. That year the candidate who won his party’s primary vote, Woodrow Wilson, went on to defeat the candidate who lost his party’s primary vote, William Howard Taft. As a rule, the candidate with the stronger primary performance wins against the candidate with the weaker primary performance.
For elections prior to 1952 all primaries were included. Beginning in 1952, only the New Hampshire Primary has been used, as a rule. South Carolina has been added for elections since 2008. Both Obama then and Hillary Clinton in 2016 enjoyed strong support in a large and most loyal Democratic constituency, African-Americans, who are few in numbers in New Hampshire.
For the record, the PRIMARY MODEL, with slight modifications, has picked the winner of all but two of the presidential elections since it was introduced in 1996. Both misses came under extraordinary circumstances. The 2000 case featured a protracted recount dispute in the pivotal state of Florida, which was not settled until a-5-4 ruling by the U.S. Supreme Court Bush v. Gore. The other one was the 2020 election, which sparked protests by the losing side over the handling of mail ballots and other voting procedures adopted in the wake of the Covid Pandemic. Trump and many of his supporters claimed the election was stolen, prompting a mob to storm the Capitol on January 6. For elections from 1912 to 1992, the PRIMARY MODEL picks the winner, albeit retroactively, every time except in 1960, also one not without controversy about the true winner.
To be sure, the decision to allocate Biden’s 2024 primary record to Harris in order to fashion a forecast for the general election will strike some observers as a stretch. Didn’t Harris flame out as a presidential candidate in 2020 before a single vote was cast in primaries or caucuses that year? Indeed. But what matters in 2024 is that the sitting president gave her a full-throated endorsement in the same breath that announced his departure from the race. What is more, within a couple of days Harris was able to nail down support for her candidacy from enough delegates to clinch the nomination at the upcoming national convention. Not a single challenger threw their hat in the ring. There is no denying that Harris enjoys as much support as Biden mustered in his primary campaign. Perhaps even more so since she does not carry the age-related liabilities of the sitting president. Using Biden’s primary score as a proxy for Harris is reasonable and justified.