With just a few weeks left, the Virginia gubernatorial election between Democrat Terry McAuliffe and Republican Glenn Youngkin is getting tighter. While in August McAuliffe held a 6- to 8-point advantage over his opponent, in several recent polls, the difference between the two candidates is within the margin of error.

The tightening race has motivated some of the most notable names in the Democratic Party to campaign with McAuliffe. President Biden, former president Barack Obama, House Speaker Nancy Pelosi (Calif.), first lady Jill Biden, Atlanta Mayor Keisha Lance Bottoms and former Georgia gubernatorial candidate Stacey Abrams will all have appeared with McAuliffe before Election Day. Given the close race and the fact that Virginia is the first major test for the Democratic Party since Biden’s election, that’s hardly surprising.

In addition to bringing their general star power, Obama, Abrams and Bottoms’s appearances are all meant to attract support from and mobilize African American voters — a key voting bloc in a state that’s becoming more racially and ethnically diverse.

So will these visits boost McAuliffe’s chances in November by attracting and mobilizing White liberals and voters of color? Previous research doesn’t offer a clear answer. But when combined with serious outreach, these visits may indeed be key to mobilizing Black voters.

Why should campaign stops from prominent politicians matter?

In theory, these campaign visits should bring a number of advantages that could boost votes for McAuliffe.

First, partisan figures can and do mobilize a party’s base and increase the likelihood they’ll turn out to vote. Political scientists Rob Mellen Jr. and Kathleen Searles, in their study of presidential midterm visits between 1986 and 2006, find that turnout is often higher in congressional districts where candidates campaign with the president. The president’s appearance is supposed to attract attention to campaigns during off years, when fewer people vote than in presidential elections.

That may be partly due to media coverage of these visits. When candidates appear with high-profile politicians, they often receive a surge in coverage from local media. For example, political scientists Patrick Sellers and Laura Denton show that when congressional Republican candidates appeared with George W. Bush during the 2002 midterms, they received significantly more local media coverage than when they appeared alone. This coverage not only increases interest in the campaign, it also tends to be more positive — which helps increase the candidate’s appeal.

Finally, prominent political players’ visits are often associated with an increase in campaign donations. Candidates who appear at rallies with high-profile people, whether politicians or celebrities, generally see a sharp increase in financial support. These resources can be important in putting competitive candidates over the finish line.

But in practice, do party leaders’ visits actually help candidates?

While in theory campaign visits should matter, in practice, results from political science research are mixed. Political scientists Sellers and Denton and Jeffrey E. Cohen, Michael A. Krassa and John A. Hamman independently investigated presidential visits supporting Senate candidates’ midterm election campaigns between the 1980s and early 2000s; both groups found that these visits increased votes for those candidates.

However, today, Americans are far more polarized, and fewer voters vacillate between candidates — suggesting that the prominent officials’ visits may matter less. Political scientists Mellen and Searles found that presidential visits increased turnout for the candidates they appeared with, although these visits didn’t actually win over any new voters. Similarly, political scientists Alan Abramowitz and Costas Panagopoulos found that President Donald Trump’s appearances with GOP senators did not win over any new voters during the 2018 midterm elections.

A significant amount of research shows that prominent politicians generally campaign with candidates only in areas where the prominent public figure is already popular. As a result, the high-profile politicians tend to visit areas where voters already support the candidate, leaving little room for improvement. In other words, visits from key Democratic Party players may be unlikely to change anyone’s minds heading into November. However, they may matter in motivating some supporters to vote on Election Day.

What about visits targeted at mobilizing Black Virginia voters?

What is unique about McAuliffe’s visits is that they are targeted in part to get voters of color to vote. In the past several years, when voters of color have stayed home instead of voting, it has seriously damaged Democratic candidates’ chances.

Some of Chris Stout’s own research looked at Black Senate and gubernatorial candidates who campaigned between 1982 and 2010. When these candidates appear with prominent Black figures while also offering substantive policy proposals, they are more likely to win Black voters’ support and get them to cast ballots. Other research finds that when prominent Black figures appear with White candidates, those candidates similarly win over more Black voters and get them to the polls. A candidate’s connections to Black public figures signals empathy for a racial group that is often overlooked and whose leaders are often kept at arm’s length in competitive races.

More particularly, several studies have shown that both Obama and Abrams have been very successful in getting Black voters to cast ballots. Their appearances, in other words, aren’t just symbolic; their presence and their organizations in Virginia may indeed bring out Black voters, who make up about one-fifth of the state’s voters.

What does all this mean for McAuliffe?

Overall, these visits probably won’t help McAuliffe win over a large swath of new voters. But when combined with strong policy proposals, McAuliffe’s campaign appearances with Obama, Abrams and others may indeed get key parts of the Democratic base to go to the polls. That could make all the difference in a tight election.

Karina Mondragon is a recent political science graduate from Oregon State University

Cara Nixon is a political science and applied journalism student at Oregon State University and the city editor for the Daily Barometer.