Post-debate sentiment shift reveals surprising trends

The first presidential debate between Kamala Harris and Donald Trump is in the history books, but how was it perceived by the US public? Every two weeks, Prolific surveys 2,000 nationally representative US voters to capture sentiment around voting intentions and current affairs.  

Our latest results focusing on the debate reveal some interesting trends that could impact the electoral landscape as we approach November. Here's what we found. 

Republican base showing cracks 

While Trump maintains strong support among Republicans, with 86% still planning to vote for him, there are signs of growing unease within his base. A significant 40% of Republican voters admitted feeling worried after watching his debate performance. It shows there’s some anxiety, which could potentially impact voter turnout or even lead to last-minute vote switching.

Adding to these concerns, only 16% of Republicans rated Trump's performance as excellent. Tepid enthusiasm from his core supporters might signal trouble for the Trump campaign, especially if it translates into reduced volunteer efforts or campaign donations in crucial swing states.

Harris scores points across the aisle

In contrast, Kamala Harris has managed to impress viewers on both sides of the political divide. A notable 24% of Republican voters rated her debate performance as either excellent or good, while 25% conceded she won the debate. Cross-party appeal could play a central role in swaying undecided voters or even peeling away some moderate Republicans.

Overall, 54% of respondents gave Harris high marks for her debate showing. Her ability to connect with a broad audience and articulate her positions clearly seems to have resonated with many viewers, regardless of their political affiliation.

Debate victor: Harris takes the crown 

When asked directly who won the debate, a clear majority of 57% chose Kamala Harris. It’s a decisive victory in the public’s perception and could provide a significant boost to the Democratic campaign.

Harris performed especially well with key demographics. Young voters showed strong support, despite 27% of 18-24 year olds admitting they didn't watch the debate. This suggests Harris has cultivated a positive image among younger voters that extends beyond her debate performance.

African American voters emerged as one of Harris' strongest bases of support, with an overwhelming 70% declaring her the debate winner. Such enthusiasm among a critical Democratic voting bloc could be vital for turnout efforts in key states.

Demographic variations mean the election mood is a mixed bag

The debate seems to have influenced overall sentiment about the election, though reactions are mixed. Just over 40% of voters reported feeling optimistic about the election after watching the debate. The numbers suggest that for a significant portion of the electorate, the candidates' performances reinforced or boosted their confidence in the democratic process.

It’s not all positives, however. Of those polled, 30% expressed concerns about the potential outcome and indicated a continued sense of apprehension among a sizable portion of the electorate. Various factors could be creating this anxiety, including worries about election integrity, potential post-election challenges, or concerns about either candidate's ability to govern effectively.

Interestingly, optimism was notably higher among African American voters, with 58% feeling confident about the election's direction. The good mood could reflect enthusiasm for Harris' historic candidacy or approval of the Democratic ticket's policy positions.

Demand for round two 

The debate clearly left voters wanting more, with 61% calling for a second face-off between the candidates. Appetite for additional debates was particularly strong among young voters—67% of 18-24 year olds strongly advocated for another showdown.

There’s a clear desire for more direct comparisons between the candidates, which suggests that many voters are still making up their minds. This indicates that debates remain valuable for voter education and engagement, even in an era of fragmented media consumption.

What comes next? 

Despite enthusiasm, there aren’t currently any plans for a second debate, with Donald Trump indicating he’s not interested. But with a little over six weeks to go, that could all change, especially as there are still questions around: 

• Whether the unease among Republican voters grows, or if Trump manages to shore up his base.
• If Harris can maintain her post-debate momentum and continue to appeal across party lines.
• Voter optimism or anxiety about the election, and if it will evolve as we get closer to November.
• If younger voters' enthusiasm translates into higher turnout.
• If additional debates will impact voter perceptions and preferences. 

Prolific has an important role to play, surveying the American population bi-weekly to see if sentiment changes between now and November. 

How Prolific polls US politics

We're committed to transparency and data quality. Our US polls use a nationally representative sample of 2,000 US participants, carefully selected to match key demographic characteristics of the US population.  We then apply our custom multiple-regression with post-stratification (MRP) pipeline to further weight the data by seven factors that describe the makeup of the US population (you can find the full details of this process here). 

Our quick turnaround time—typically completing polls within 24 hours—allows us to capture immediate reactions to major events like debates. A capability to respond quickly, combined with our large and diverse participant pool, enables us to provide timely and accurate insights into public opinion.

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