In a recent 538 forecast, an analysis was conducted to gauge the possible outcome of a hypothetical 2024 election between Vice President Kamala Harris and former President Donald Trump. Taking into account limited polling data available, the study aimed to shed light on whether Harris would fare better against Trump than President Joe Biden.

The analysis began by examining post-debate polls conducted by Ipsos's KnowledgePanel, which revealed a significant setback for President Biden. Described as one of the worst debates for an incumbent president, only 21 percent of viewers believed he performed the best, while the average watcher rated his performance as "poor." In contrast, despite numerous falsehoods, 60 percent of viewers felt that Trump performed the best.

Following the debate, Biden faced mounting pressure to step aside in favor of a Democrat with a stronger chance of defeating Trump. Some op-ed columnists, including The New York Times editorial board, called for Biden's withdrawal, citing the urgency of preventing a Trump victory. Elected Democrats, such as Rep. Lloyd Doggett, also publicly suggested that Biden should consider stepping aside.

Should Biden choose to step down, Harris is considered the most likely candidate to take his place as the Democratic nominee, primarily due to her position as vice president. Although it is difficult to definitively determine whether Harris would outperform Biden, the analysis sought to quantify her odds using the information available.

However, polling data specifically pitting Harris against Trump is relatively scarce, with just over a dozen polls conducted between April 1 and July 2. Despite this limitation, national polls comparing Harris and Trump showed relatively similar results to those of Biden. For instance, in a March Fox News poll, Trump led Harris by 6 points and Biden by 5 points, well within the margin of error.

While Harris seemed to gain some ground in a June 28-30 CNN/SSRS poll, where she trailed Trump by only 2 points compared to Biden's 6-point deficit, this shift may be within the margin of error. As a result, the forecast model for a Harris versus Trump matchup predicted her chances of winning the Electoral College slightly higher, at 38-in-100 compared to Biden's 35-in-100.

On a state-by-state level, Biden appeared stronger than Harris in Pennsylvania and Wisconsin, while Harris had higher odds than Biden in Nevada. Furthermore, Harris demonstrated a marginally better performance in the forecasted national popular vote compared to Biden, with the model predicting that Trump would outpace Harris by 1.5 points and Biden by 2.1 points.

Nevertheless, the analysis acknowledged the absence of Harris-versus-Trump polls that included the independent candidate Robert F. Kennedy Jr., who tends to receive slightly more votes from Democrats. This factor could potentially impact the final results.

However, when considering factors beyond polling data, Harris performed less favorably against Trump in a full 538 forecasting model. In this model, which incorporates non-polling economic and political variables ("fundamentals"), Biden held a 48-in-100 chance of winning the Electoral College, while Harris only had a 31-in-100 chance.

Part of this discrepancy is attributed to the advantage the model conferred on Biden as the incumbent president. However, the model did not factor in whether presidents' approval ratings and economic growth impact incumbents differently than non-incumbents from the same party. This aspect could potentially sway results in favor of Harris, depending on individual perspectives.

Despite the forecast analysis, Biden's core problem may extend beyond current polling. Concerns regarding his age and competency persist and tend to worsen over time. Consequently, while uncertainties exist regarding potential alternatives to Biden, such as Harris, Democrats may be inclined to take the risk given what they have come to realize about Biden.

Ultimately, deciding the Democratic Party's nominee for president will require more than just considering the polls. The uncertainties surrounding other potential candidates and the extensive scrutiny that accompanies the presidential and vice presidential positions make it crucial for Democrats to weigh all factors before making a decision.