The 2024 election is finally here, concluding a battle between Democratic nominee Kamala Harris and Republican nominee Donald Trump for the presidency, and the respective parties overall for control of Congress. Here’s a snapshot of what polls showed about the election at the beginning of October.
Who was leading the presidential election at the beginning of October? Before dropping out in July, President Biden narrowly trailed former President Trump in the polls. Then, after Biden’s poor debate performance at the end of June, Trump’s lead climbed up to 3.2% nationally, according to the FiveThirtyEight polling aggregator. However, Kamala Harris had led steadily in the polls through the start of October since replacing Biden as the Democratic candidate.
According to the FiveThirtyEight polling aggregator, Harris led Trump by 2.5% nationally on October 7th. Out of the seven constituencies considered to be swing states, Harris led in four, with some averages mirroring her national lead (+1.6% in Wisconsin; +1.5% in Michigan) and others resting on razor-thin margins (+0.9% in Nevada; +0.6% in Pennsylvania). Trump led in three, by varying margins (+1.6% in Arizona; +1.3% in Georgia; +0.8% in North Carolina). According to the polls held at the start of October in swing states, Harris would win the election narrowly, but a swing of little more than a percentage point has the potential to change the results.
However, these polls don’t tell the whole story. Trump has famously beaten polling projections across his political career, overperforming his national average by 1.8% in 2016 and 3.9% in 2020, and concurrently doing better than expected those years in swing states. In addition, most polls from this point in the campaign had a margin of error of about 3%, meaning that the 2.5% lead for Harris could realistically have been anything from a 5.5% lead for Harris to a 0.5% lead for Trump.
Who was poised to take control of Congress at the beginning of October? After the 2022 elections, Congress was left divided, with Democrats leading the Senate (51-49) and Republicans leading the House of Representatives (220-211). At the beginning of October, FiveThirtyEight polling indicated that more voters would prefer Democrats in Congress, though only by a small margin (+2.0%). However, just as in the presidential election, the national polling was thought to skew more in favor of Democrats than the eventual outcome, since control of Congress is determined by elections in individual states and districts. This creates a phenomenon (similar to the Electoral College) where national polling better reflects the preferences of blue voters in blue constituencies, red voters in red constituencies, and undecided voters in red or blue constituencies when congressional control hinges mostly on undecided voters in the rare competitive constituencies.
The 2024 Senate elections offered an extremely favorable map for Republicans, with Democrats forced to play defense on three seats in red states (Montana, Ohio, and West Virginia) and five seats in swing states (Arizona, Michigan, Nevada, Pennsylvania, and Wisconsin). Meanwhile, Republicans only had to defend an array of seats considered to be safely red, with only Texas (R+3.4%), Florida (R+4.2%), and Nebraska (R+2.6%; technically the Democratic Party did not run a candidate in this election, though independent candidate Dan Osborn’s positions indicated he was far more likely to vote with them than the Republican incumbent) holding elections that were considered barely winnable (but extremely unlikely) pickups for Democrats. With the advantages that came with this Senate map, Republicans were almost certain to take control of the Senate, with a hypothetical potential of 57 seats (not including safe blue seats).
Regarding the House of Representatives elections, Democrats appeared poised for a narrow majority, since those elections tend to line up better with the national polling. Democrats won control of the House in 2018 and 2020 when they led the national poll, and Republicans won their current majority in 2022 with a lead in the national poll as well. It seems that another two years of divided government may be likely, which would make it very difficult for the winner of the presidential election to implement their agenda (and likely setting up losses for their party in the 2026 elections).
What do the polls tell us a day prior to Election Day? Elections change fast, and 2024 was no exception. What looked like a lead for Kamala Harris heading into November changed to a Trump advantage with only a couple weeks to go. Such changes show that with such small margins and rapidly changing political climates, no poll can truly claim to predict the outcome of the 2024 presidential and congressional elections before November 5th, whether in October or the day before.
