This election season has been full of dramatic events—the attempted assassination of Donald Trump, Joe Biden’s withdrawal from the race, and Kamala Harris’s sudden catapulting to the front of the Democratic ticket—and now provides still more suspense as we enter the final days before Harris announces her running mate. But how consequential is her decision actually? How will it influence the political landscape?
In general, political scientists tend to find that the selection of a VP candidate has only a very modest impact on the presidential candidate’s electoral prospects. The so-called home state effect (the ability of the VP candidate to positively impact electoral results in their home state in November) typically is quite minimal, and overall, the favorability of a VP pick in the eyes of voters rarely translates into much support for the presidential candidate who selects them. Relatively speaking, the biggest electoral impact that the choice of a VP candidate tends to have is indirect: what the pick says about the judgment of the president who makes the selection. Trump’s selection of Mike Pence is perhaps a good example of this dynamic, as the selection effectively demonstrated Trump’s commitment to evangelical Christians and conservative Republicans, even if its effects in other respects were much more muted. Christopher J. Devine and Kyle C. Kopko highlight the significance of indirect effects of the VP selection in their 2020 book, Do Running Mates Matter?, and conclude that the best strategy for presential candidates is to avoid choosing a VP in order to win the election (hoping that the VP candidate’s popularity mobilizes support within some state or from some demographic group) and instead focus on choosing someone well-qualified to hold the office whose selection will be seen to reflect good judgment on the part of the presidential candidate.
It may prove hard for Harris to follow this advice. In a highly divided electorate in which elections routinely have been decided by razor-thin margins, even a minimal home-state effect could still make a difference. Trump lost Pennsylvania in 2020 by just 80,000 votes (2% of all votes cast) and won the state by an even smaller margin in 2016 (44,000 votes, or just .7% of total votes cast), a situation that might tempt Harris to pick Pennsylvania Governor Josh Shapiro, who was elected in 2022 with over 56% of the vote. A similar temptation might lead Harris to pick Arizona Senator Mark Kelly, who has twice won close elections in a state that, in 2020, Biden won by just 11,000 votes.
Suppose Harris decides to try to win the election by selecting a VP pick. In that case, she will probably be drawn to select someone from the political center, as centrist voters are more likely not to have made up their minds and thus be open to persuasion. Kentucky Governor Andy Beshear may be the most centrist of all the VP possibilities Harris is thought to be considering. Governor Shapiro is himself thought to be a centrist, which could work in his favor—though the perception that he is pro-Israel, and more specifically that he played a role in shutting down pro-Gaza protests in Pennsylvania, may alienate some parts of the Democratic base. And Senator Kelly, in addition to being a former Navy combat pilot and astronaut as well as the husband of former Arizona Congresswoman Gabby Giffords, who survived an assassination attempt, has been hawkish on immigration, an issue that some perceive Harris to be ineffective on, so for these reasons might do well on centrist grounds, though Kelly’s aggressive stance in favor of gun control may highlight an issue Harris wishes to deemphasize for political reasons.
At the same time, one of the oldest adages in the selection of a VP is to do no harm. VP selections can much more obviously derail electoral campaigns than win them, as evidenced in George McGovern’s selection of Thomas Eagleton in 1972 (who withdrew 18 days into his candidacy) and John McCain’s selection in 2008 of Sarah Palin (who did damage to McCain’s chances following her first TV interview as a candidate). What makes someone risky? Too little political experience can be one kind of risk. Here, it is perhaps relevant to mention that Governor Shapiro held office for just two years and never debated his rival in the 2022 gubernatorial election. More experienced politicians like the aforementioned Kelly and Beshear or Minnesota Governor Tim Walz, who himself has twice won hard-fought elections against moderate Republicans—may be seen as less risky. On the other hand, too much exposure potentially creates risks as well, as reflected by current GOP VP nominee J.D. Vance, whose unusually high media exposure as an author, commentator, and now politician has provided his rivals with dozens of potentially embarrassing statements and soundbites from his past.
Whatever Harris’s decision, it will generate a situation, unusual in modern times, in which three of the four individuals on the GOP and Democratic tickets will not have been selected through the primary process (or, for that matter, even been candidates for president when the electoral season began). This rather undemocratic circumstance will, of course, be somewhat rectified in November when voters get their say. By the early fall, Harris’s VP choice will likely seem incidental to the race. But by 2028 and beyond, though, it may prove quite consequential since historically, VP candidates have gone on to play outsized roles in their future political lives, as witnessed by Harris’s current status as the presidential nominee.
Jeffrey Edward Green
Director of the Andrea Mitchell Center for the Study of Democracy & Professor of Political Science at the University of Pennsylvania
Green’s most recent book is: Bob Dylan: Prophet Without God (Oxford, 2024)
