Do vice-presidential candidates affect presidential races?

“Historically, the vice president, in terms of the election, does not have any impact,” Donald Trump declared onstage Wednesday at the National Association of Black Journalists convention. This was a bizarre thing for a candidate to say when asked whether his running mate would be ready to serve as president if needed.

Writing in The Atlantic, Lora Kelley digs into the more complicated reality of what role nominees for vice president have in determining election outcomes. I took a lot of hope from this paragraph in particular:

Christopher Devine, an associate professor at the University of Dayton and a co-author of Do Running Mates Matter?, … and his co-author, Kyle Kopko, have not found clear evidence that a running mate’s “home-state advantage” or demographic appeal play a decisive role in whom people vote for. One exception was the 2020 election, when, Devine and Kopko observed, Vice President Kamala Harris likely delivered Democrats a small number of additional votes among Black, women, and Black women voters. But they saw no proof that Mike Pence actually pulled in evangelicals in 2016—though Devine noted that some Republicans reluctant to support Trump pointed to Pence, a more established and traditional politician, as a way to save face when they voted for him anyway.

I think that suggests that, at worst, any reasonable pick of a running mate for Kamala Harris probably won’t hurt the ticket. Harris will draw voters in. Also, the Harris campaign probably doesn’t need to be as concerned about picking a white man from a swing state as the punditry generally seems to think.

(On the other hand, I would love to see U.S. Senator Mark Kelly of Arizona be her pick. I think his Navy combat and NASA Space Shuttle experience, being the husband of a survivor of a shooting that was motivated by political extremism, and living less than ninety miles from the U.S.-Mexico border, all give him perspectives and credibility on a unique set of important issues: war and peace, big science, guns, political violence and polarization, immigration, and U.S.-Latin American relations. But I digress.)

Especially in combination with this polling news about J.D. Vance from Business Insider on July 24:

On the heels of last week’s Republican National Convention, the Ohio senator is the least-liked vice-presidential candidate since 1980, CNN found in a polling analysis. It noted the data applied to nonincumbents.

Unlike Pence having potentially helped Trump non-enthusiasts vote Republican in 2016, there’s even some evidence Vance could be a drag on the Republican presidential ticket in 2024:

Vance heavily underperformed in his 2022 Ohio Senate race, at least compared with how other Republicans performed in the state that year.

Lora Kelly. “The Problem With Donald Trump’s VP Theory.” The Atlantic. August 2, 2024. https://theatlantic.com/newsletters/archive/2024/08/the-problem-with-donald-trumps-vp-theory/679354/.

Alice Tecotzky, John L. Dorman. “JD Vance breaks polling records in the worst way.” Business Insider. July 24, 2024. https://businessinsider.com/jd-vance-lowest-vice-president-approval-rating-republican-convention-2024-7.