We’ve all been there: it’s a hot summer day and you head to your local ice cream parlor for two scoops of double fudge chocolate chips. But alas, today they are all gone, and all they have left is vanilla. You’re not exactly happy with it, but you order a scoop of it anyway, because hey, a little 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 final time this year, leaving just one major event on the campaign calendar: Tuesday’s vice presidential debate between Senator J.D. Vance of Ohio and the governor of Minnesota. . Tim Walz.

But the truth is, it’s just not the same. Typically, fewer people watch vice presidential debates than presidential debates. And while presidential debates have historically been one of the few things that can actually make a dent in the polls, vice-presidential debates don’t have the same track record. It’s true, she can has some influence on how voters feel about the vice presidential candidates themselves, but ultimately running mates do not influence many people’s votes.

Vice presidential candidates tend to be overshadowed by their counterparts at the top of the list – and vice presidential debates typically do that too. According to Nielsen, presidential debates have attracted an average audience of 65.7 million people since 2008. But vice presidential debates averaged only 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 — so have past vice presidential debates actually changed the trajectory of the race? That turns out to be a difficult question to answer.

Normally we would check this by comparing what the polls said before the debate with what they said a few weeks later. If the polls were to shift significantly in the aftermath of the debate, it would indicate (but not confirm!) that the debate made a difference.

But the problem is that the most recent vice presidential debates were very quickly followed by 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 emerge in the polls before it is (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 don’t move much in the aftermath of 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 president. presidential debate.

The only time this century that national polls rose more than 1 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 affected the race – perhaps the impact simply didn’t have time to show up in the polls in the short period 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 barely changed in that time.

None of this is to say that vice presidential debates don’t have any impact. It turns out that they can have small effects on the popularity of the vice presidential candidates themselves. We calculated poll averages of the favorable and unfavorable ratings of six recent non-incumbent vice presidential candidates around the time of their vice presidential debates.** Most of them saw a small change in their net favorable rating (favorable rating minus unfavorable rating) after the debate. Specifically, their net favorable rating had shifted by an average of 2 points two weeks after the debate.

Going into Tuesday night’s debate, Walz is significantly more popular than Vance. As of Tuesday at 9 a.m. Eastern, Walz has an average net favorable rating of +4 points (40 percent favorable, 36 percent unfavorable). Vance, meanwhile, is underwater, with an average net favorable rating of -11 points (35 percent favorable, 46 percent unfavorable). Based on history, each candidate will have the opportunity to change this during the debate. But it would also be a big surprise if the debate changes Americans’ general feelings about the vice presidential candidates (i.e. if Vance suddenly becomes more popular than Walz).

And remember: vice presidential candidates themselves don’t matter much. Except in extraordinary circumstances, voters decide based on the people who can actually wield power—the presidential candidates—and not those who could inherit that power if something goes wrong. So even if the debate changes Americans’ perceptions of the vice presidential candidates, it probably won’t change their actual votes (as history has shown) — because few people base their votes on the vice presidential candidates to begin with.

G. Elliott Morris contributed research.

Footnotes

*Using our current polling average methodology, applied retroactively.

**Again, retroactively using our current poll average method for the preferred poll. We had enough data to do this for all non-incumbent vice presidential candidates over the past twenty years, except then-Senator. Joe Biden in 2008.