ABC News Photo Illustration / REBA SALDANHA
Is the 2024 Republican presidential primary already over? If you just look at the polls, you’d be forgiven for thinking so. Consider the state of the states: Several polls published last week showed former President Donald Trump leading in Iowa (with 42 percent to Florida Gov. Ron DeSantis’s 19 percent and South Carolina Sen. Tim Scott’s 9 percent), New Hampshire (at 50 percent versus DeSantis at 11 and businessman Vivek Ramaswamy at 10 percent) and South Carolina (at 48 percent versus 14 percent for both DeSantis and Scott). And in national polls, Trump currently has the support of 50 percent of GOP primary voters1 — a slide of 2 percentage points since last Wednesday’s GOP primary debate, but still a commanding lead over his opponents.
Yet despite these dominant margins, our study of the history of primary polling suggests that it’s still too early to completely write off Trump’s competitors. Here at FiveThirtyEight, we are big believers in the predictive power of early election polling — where it is warranted. While we have found that early national polls tend to predict who will win primaries relatively well, there is a ton of volatility that prevents us from providing the type of clarity analysts want from forecasts. At this point in the 1992 Democratic primary, for example, future President Bill Clinton had not even announced his campaign. And at this point in the 2020 Democratic primary campaign, former South Bend, Indiana, Mayor Pete Buttigieg was garnering just 8 percent in polls of Iowa; come February, he won 25 percent of the popular vote in the caucuses.
To account for this uncertainty, I wrote a crude statistical model to translate national polling averages at this point in past campaigns into odds of winning presidential nominations. This model gives us a way of answering a key question of polling analysis: How durable is Candidate X’s lead given historical ranges of movement and measurement error in the polls? As of writing, this model gives Trump around a 78 percent chance of winning the nomination (sound familiar?) based on the polls. But there’s a lot of uncertainty surrounding how much we can trust surveys to produce a reliable signal in this primary — the biggest problem being that, historically, only a handful of candidates were polling around 50 percent nationally at this point in the cycle. Thanks to that small sample size, Trump’s “true” win probability2 could be as low as 54 percent.
Trump is the heavy favorite in the GOP primary
Before getting into how the model works, let’s quickly take stock of the state of the race. Trump is currently at 50 percent in our average of national Republican primary polls. DeSantis, his closest competitor, is in a distant second place with 15 percent. Ramaswamy is currently enjoying a bit of a bounce: Over the last month, he has risen from 6 to 10 percent in national polls.