With two weeks to go, the Republican candidate now has a slight lead

Oct 21st 2024

For the first time since August, Donald Trump has overtaken Kamala Harris in The Economist’s statistical model of America’s presidential election. Our latest forecast shows that Mr Trump has a 54% chance of returning to the White House, up six percentage points during the past week. Although the race still remains more or less a coin toss, it is now weighted slightly in Mr Trump’s direction.

The shift in our model reflects a steady narrowing of Ms Harris’s lead in national polls during the past month. Shortly after she became the Democrats’ presumptive nominee in July, a chunk of respondents who had previously said that they were undecided or backing third-party candidates started supporting her, increasing her national vote share from 46% to 49%. Many of these voters were probably disillusioned Democrats.

Now, Mr Trump appears to be benefiting from similar partisan consolidation, as Republican-leaning undecided voters “come home” to their party’s nominee. Whereas Ms Harris’s support has been flat for two months, Mr Trump’s has ticked up from a low of 45% in August to 47% now. This has cut his deficit in the national vote from a high of 3.7 percentage points to just 1.6.

Our forecast still gives the vice-president a 74% chance of winning the popular vote. However, the reason that Mr Trump has pulled ahead is his advantage in the electoral college. State-specific polls published in the past week confirm that Mr Trump’s position has strengthened slightly in the plausibly decisive states, just as it has nationwide (see chart). The data do not support the claim by some Democratic partisans that Republican-aligned firms are “flooding” polling averages with Trump-friendly results: the former president has also gained ground in surveys by pollsters that tend to publish good numbers for Democrats.

Just as in 2016 and 2020, the Democratic nominee is faring worse in swing-state polls than in national surveys. The candidates are roughly tied in Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin, and Mr Trump is up by almost two percentage points in Arizona and Georgia. As a result, our model now estimates that Ms Harris needs to win the national popular vote by at least 2.5 percentage points to be favoured in the electoral college, up from 1.8 points in August.

Our model’s expected results in each state have moved only slightly. For example, Mr Trump’s average predicted vote share in Pennsylvania (excluding third parties) has risen by 0.5 percentage points during the past week—a fraction of the 2.5 points Democrats gained in the state from the day Joe Biden exited the race to Ms Harris’s high-water mark on September 19th. However, because the race is roughly tied, even tiny shifts in polling can have a big impact on estimated probabilities of victory.

With just two weeks left in the campaign, there is little time left for polling averages to move much. That is no guarantee that the election will be close. It would take only a modest polling error, well within the range of historical variation, for either candidate to sweep the swing states and win a decisive victory. In fact, our model finds that there is a nearly 50/50 chance that one of the two candidates gets at least 306 electoral votes—the number that Mr Biden won in 2020, and that Mr Trump did in 2016. ■

Excerpts: The Economist