Has Kamala Harris reached the ceiling of her ability to make gains against Trump?

With less than three weeks to go before Election Day, the polling at this point is clear: Kamala Harris and Donald Trump are effectively tied.

Harris has led the Democratic ticket for less than three months, but in that short time she has galvanised Democratic voters and significantly increased the popularity of the Democratic ticket. Yet, current levels of US political polarisation and, perhaps more notably, calcification, make one wonder just how much more support she could win.

In other words, few Americans are undecided in their views of Donald Trump – he galvanises both his base and his opponents alike – so there are simply not many American voters remaining for Harris to try to win over.

Initial momentum has plateaued

When 81-year-old Joe Biden led the Democratic ticket in early 2024, only 55% of Democrats and Democratic-leaning voters were enthusiastic about the election.

While the 2020 presidential election between Biden and Trump broke records for US voter turnout, the 2024 redux was looking like it would break the opposite sort of records – for voter disinterest.

That is, at least, until Harris assumed the top of the Democratic ticket on 21 July 2024. Within a month of Biden stepping down as the party’s nominee, Democratic enthusiasm for their significantly younger candidate jumped 23 points to 78%. This eclipsed not only levels of enthusiasm that Democrats had for Barack Obama in 2008, but also the levels of enthusiasm that Republicans currently have for Donald Trump.

Harris’ momentum saw the race quickly move on from deep analysis of the “double haters” – the record 25% US voters who disliked both Trump and Biden and were simply deciding which they hated less. With a much closer contest now likely, attention shifted to key swing states such as Pennsylvania, where Harris closed Trump’s five-point lead over Biden to now be around even.

Small changes can make a big difference

Harris’ ability to make the Democratic ticket competitive should not be undervalued. After all, as recently as June 2024, she was one of the few Democratic politicians who actually had a lower national approval rating than Joe Biden.

With that said, the momentum for Harris should not be seen as a sea change across the country. As much as she energised a previously lacklustre Democratic ticket, approval of Harris among self-described Independent voters only increased from 36% to 43% in the same timeframe. Republican approval of Harris decreased slightly from 6% to 4% over the same period.

Ultimately, even the slightest of changes can completely shift the nature of the race, particularly given how slim the margins have been in the last two presidential elections. In the 2016 presidential election, for example, Trump’s margin of victory was some 75,000 votes across three swing states. In 2020, Biden’s margin of victory was about 45,000 votes across three swing states.

Harris or Trump’s 2024 margin of victory very well may be less than 0.03% of the US electorate, making this potentially the closest US election in decades.

Has support for Harris peaked?

For the first half of 2024, Trump polled considerably ahead of Biden in the key swing states that will most likely decide the US election. Then, within weeks of Harris becoming the presidential nominee in July, the difference in the swing states between Trump and his opponent shrank to around 1-2 percentage points.

Now, nearly three months later, the polling is essentially unchanged – remaining well within the standard margin of error of around ±3%.

As much as Harris has eclipsed Biden in the race against Trump, there is no denying the statistical reality that Harris is no longer gaining ground on Trump in the way that she was in the early weeks of her candidacy.

Some have argued that Harris’ liabilities – and perhaps the reason she has stalled in the polls – are that Americans remain fairly negative on the economy, she is in the incumbent administration instead of on an outsider ticket, and that many view her as simply too progressive.

Yet judging by the fact that Harris appears to be polling better than “a generic Democrat” – who generally are more popular than any other Democrats because they are not real people with real positions – it’s perhaps more likely that in these polarised and calcified times, Harris very well may have simply peaked as high as any other Democratic candidate possibly could.

With American voter intentions barely shifting after an insurrection, pandemic and assassination attempts, it’s hard to imagine Harris can do much better than she already is doing.

Harris’ best strategy for success on November 5 may therefore need to be less focused on winning over more of the very few undecided voters remaining, and instead more focused on simply getting her energised supporters to turn up on Election Day.

Jared Mondschein does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.