We've all been there: It's a hot summer day and you stop by your local ice cream shop to grab two scoops of Double Fudge Chocolate Chip. But alas – today they are all out and all they have left is vanilla. You're not happy about it, but you order a scoop anyway because, hey, some ice cream is better than no ice cream.

That's basically the situation we find ourselves in with debates. Barring a last-minute change of heart, former President Donald Trump and Vice President Kamala Harris have debated for the last time this year, leaving only one major event remaining on the campaign calendar: the vice presidential debate between the Ohio senator, JD Vance, and Minnesota Gov. Tim Walz on Tuesday.

But the truth is, it's just not the same. Typically, fewer people watch vice presidential debates than presidential debates. And while presidential debates are historically one of the few things that can actually impact the polls, vice presidential debates don't have the same track record. That's right, she may They have a small influence on how voters feel about the vice presidential candidates themselves — but at the end of the day, the candidates have no influence on many people's votes.

Vice presidential candidates tend to be overshadowed by their colleagues at the top of the candidate list — and vice presidential debates tend to do the same. According to Nielsen, presidential debates have drawn an average audience of 65.7 million people since 2008. But the vice presidential debates drew an average of just 54.1 million viewers. In the last three presidential elections, the vice presidential debate has been the least-watched debate of the fall.

But 54.1 million people is still a pretty big audience — have past vice president debates actually changed the course of the race? It turns out that answering this question is difficult.

Normally we would check this by comparing poll results before the debate with those taken a few weeks later. If the poll numbers shift significantly during the debate, this would suggest (but not confirm!) that the debate made a difference.

The problem, however, is that the recent vice presidential debates have been very fast-tracked presidential Debates. For example, in 2000, there was a presidential debate six days after the vice presidential debate. In 2008, 2012, and 2016, there was a presidential debate five days after the vice presidential debate. And in 2004, there was a presidential debate just three days after the vice presidential debate!

That doesn't leave much time for the (potential) impact of the vice presidential debate to show up in the polls before they are (potentially) overwhelmed by the impact of the presidential debate. The chart below shows the 538 national poll averages* from the 2000-2020 presidential elections in the days immediately before and after the vice presidential debates. As you can see, they barely move in the aftermath of the vice presidential debates – and when they do move, it's usually after the presidential debate has already taken place, making it more likely that the presidential debate caused the movement and not the vice presidential debate.

The only time this century that national polls moved by more than one percentage point after the vice presidential debate but before the presidential debate was in 2000. In 2004, 2008, 2012 and 2016, the movement was negligible. Of course, this doesn't necessarily mean the vice presidential debate wouldn't have done it influenced the race – perhaps the impact simply didn't have time to be reflected in the polls in the short window of time between the two debates. But in 2020, there was no presidential debate for more than two weeks after the vice presidential debate, and the polls changed little during that time.

None of this means that the vice presidential debates have no impact. It turns out that they may have little impact on the popularity of the vice presidential candidates themselves. We calculated poll averages of the favorable and unfavorable ratings of six current, non-incumbent vice presidential candidates at the time of their vice presidential debates.** Most of them experienced small changes in their net favorability rating (favorable rating minus unfavorable rating) thereafter. the debate. Specifically, two weeks after the debate, their net positivity rating had shifted by an average of 2 points.

Heading into Tuesday night's debate, Walz is significantly more popular than Vance. As of 9 a.m. Eastern time Tuesday, Walz has an average net positivity rating of +4 points (40 percent favorable, 36 percent unfavorable). Vance, on the other hand, is underwater with an average net positivity rating of -11 points (35 percent favorable, 46 percent unfavorable). Based on history, each candidate will have the opportunity to change this slightly in the debate. But it would also be a big surprise if the debate changed Americans' general attitude toward the vice presidential candidates (e.g., if Vance suddenly became more popular than Walz).

And remember, vice presidential candidates themselves aren't that important. Except in exceptional circumstances, voters make their decision based on the people who can actually wield power – the presidential candidates – rather than those who might inherit it if something goes wrong. So even if the debate changes Americans' perceptions of the vice presidential candidates, it likely won't affect their actual votes (as history has shown) — because few people base their votes on the vice presidential candidates in the first place.

G. Elliott Morris contributed to the research.

Footnotes

*Using our current survey average method applied retrospectively.

**Again, using our current, retrospective survey average method. We had enough data to do this for all non-incumbent vice presidential candidates over the last 20 years except then-Senator. Joe Biden in 2008.