On Tuesday, Kamala Harris chose the next vice president of the United States: Minnesota Governor Tim Walz. The question is: will this increase the likelihood that voters will elect Harris as president in November?
Bottom line: probably yes, but not by much and maybe not for the reasons you think.
Many people assume that the choice of vice presidential candidate will be a deciding factor in the election. It’s a common misconception: Conventional wisdom has told them that a good choice can boost a candidate’s ticket by several points, and a bad choice can sink a campaign. But we’ve spent more than a decade studying vice presidential candidates, and our research shows that voters’ opinions of running mates don’t have much of a direct effect on the presidential vote.
Even if Walz turns out to be very popular with the American people (or quite unpopular, as Donald Trump’s running mate JD Vance has proven to be so far), that in itself won’t change many votes. The fact is that voters are electing a president of the United States, first and foremost. Yes, they are also electing a vice president, but that is much less important to them.
Another common misconception is that a running mate will “deliver” their state’s electoral votes to the presidential candidate. It’s probably no coincidence that many of Harris’s running mates come from electorally competitive states, including Walz. But our research found that there is very little evidence of a “home state advantage” for running mates. On average, the effect is close to zero. This makes us doubt that adding Walz to the ticket will in any way guarantee that Democrats will win in Minnesota or other competitive Midwestern states.
Walz wouldn’t be to blame for failing to build a decisive electoral lead (nor would Vance, for that matter). Voters don’t care all that much about running mates, but the person who is last on the ticket can help at the margins, and for good reason: The choice of a vice president tells voters something important about the person running for president.
In Harris’s case, this “first presidential act” tells voters a lot. Americans don’t know her as well as they know Joe Biden or Trump, and she has far less time than most presidential candidates to make her case. Her choice will help voters evaluate her judgment. It will also help them determine whether she makes responsible decisions, for the good of the country, or acts irresponsibly for short-term political gain. It tells people what her core values and political priorities are.
In choosing Walz, Harris has chosen a vice president who is well-qualified for the job. The two-term governor previously served six terms in Congress, where he was the ranking member of the House Veterans’ Affairs Committee. Among Harris’s finalists, he is the only one who has served in both state and federal office. Walz’s combination of executive and foreign policy experience, plus his 24 years of service in the Army National Guard, distinguish him as a plausible “second in command” in a Harris White House.
Voters are likely to reward Harris for choosing a vice presidential (and presidential) candidate with credible potential. In fact, according to our research, this is the most important criterion voters consider when evaluating a vice presidential candidate. Meeting this criterion improves voters’ opinion of a presidential candidate’s judgment, which in turn allows them to win votes.
The opposite is also true. Take the 2008 election. Our analysis showed that voters who doubted Sarah Palin’s readiness to be president lost confidence in John McCain’s judgment and became less likely to vote for the Republican ticket. In contrast, Barack Obama’s choice of Biden (a senator with decades more experience than him) increased confidence in his acumen and provided votes for the Democratic ticket. If voters also believe that Walz has White House material, it could help Harris win the election.
The pick could also benefit Democrats by reassuring their party’s progressive base of support. Harris was once seen as the most liberal member of the Senate, and voters view her as more liberal than Biden. But she faced challenges from the left during the 2020 presidential primaries, particularly over her record as a prosecutor and attorney general, and the Biden administration has often faced resistance from more progressive elements of the Democratic Party.
Our research shows that Biden’s choice of Harris as vice president shifted perceptions of his ideology to the left. Walz’s choice could also help frame Harris’ ideology, by reassuring Democrats of her progressive credibility without alienating more moderate voters. While Walz has governed Minnesota as a progressive, in Congress he represented a Republican-leaning district and was known as a relative moderate.
In November, voters will decide whether Harris made the right choice. For now, we can only rely on evidence from past elections to assess her choice. That information suggests we shouldn’t expect Walz (or Vance) to be the deciding factor in the election. But if, as we suspect, voters see Walz as a credible potential vice president who can help Harris advance her legislative agenda, he may help her reach the Oval Office.
Christopher J. Devine is an associate professor of political science at the University of Dayton. Kyle C. Kopko is an adjunct professor of political science at Elizabethtown College. His most recent book is “Do Running Mates Matter? The Influence of Vice Presidential Candidates in Presidential Elections.”
