There’s no shortage of theories about the type of running mate who would improve Democrats’ chances of beating President Trump in November: The unity approach suggests pairing a moderate with a progressive to bring both wings of the party together. With two men as the last viable candidates standing, there’s talk of putting a woman on the ticket — a female vice president would still be a first, even if it looks like a silver medal. A battleground-state strategy proposes a choice from a closely contested state needed to win the electoral college, such as Michigan, Florida, Wisconsin or Pennsylvania.

But in 2020, one option should really stand out from the rest: a black vice president.

This year’s election is likely to be decided by turnout more than by flipping voters from Trump’s column to the Democratic column. And black voters are central to any hopes Democrats have for retaking the White House. Black voting behavior, with its especially high level of electoral solidarity in general elections, is one of the most unique phenomena in contemporary American politics. So, while turnout is notoriously difficult to predict, a black vice-presidential selection stacks the deck in the party’s favor to increase enthusiasm, voter participation and chances of victory.

The buzz has been present for some time. Prominent members of the Congressional Black Caucus described the pairing of former vice president Joe Biden with Sen. Kamala D. Harris (Calif.) as the “dream ticket.” Former Georgia gubernatorial candidate Stacey Abrams, who not long ago confirmed her interest, is frequently mentioned and has been considered a contender ever since she and Biden met for a private lunch last spring. Former Massachusetts governor Deval Patrick, Florida gubernatorial nominee Andrew Gillum, Sen. Cory Booker (N.J.) and Rep. Val Demings (Fla.), who rose on the national stage as a House impeachment manager earlier this year, have all been mentioned as potential choices.

We already know that picking a partner to win his or her state doesn’t work. Kyle Kopko and Christopher Devine analyzed more than a century of election returns and found that “the vice presidential home state advantage is, essentially, zero.” Lyndon B. Johnson didn’t even deliver the South for John F. Kennedy, who probably won there thanks to his years-long courtship of disaffected southern white Democrats who’d defected to Dwight Eisenhower in 1952 and 1956. More recently, Wisconsin Rep. Paul D. Ryan was unable to get Mitt Romney over the top in 2012, and North Carolina Sen. John Edwards didn’t help John F. Kerry in 2004.

Both Biden and Sen. Bernie Sanders (I-Vt.) have indicated they would select a woman as vice president, likely in hopes of winning more female voters. Two major-party presidential nominees, Walter Mondale and John McCain, have taken this approach — it didn’t work: In 1984, Mondale and Geraldine Ferraro lost women by 10 points, a margin that snapped back to just 4 points with two men on the Democratic ballot in 1988. Similarly, in 2008, McCain and Alaska’s then-Gov. Sarah Palin lost women by 14 points. (Palin’s well-documented missteps didn’t help.) The bid by Sen. Ted Cruz (Tex.) to derail Trump’s 2016 primary momentum by preemptively announcing Carly Fiorina as his running mate also fell terribly flat.

But where home-state candidates and white female running mates have failed, a black vice-presidential candidate could, and likely would, increase the nominee’s chances of success.

History holds no evidence of this claim because neither major party has ever had an African American, or any person of color, as its vice-presidential candidate. But political science scholarship provides clues to the advantages to be gained.

Part of the reason Trump won in 2016 was that Hillary Clinton was unable to create the enthusiasm for her candidacy that Barack Obama generated in 2008 and 2012. When paired with the implementation of restrictive voting laws and inefficient processes in several states, the result was a 7-point drop-off in black turnout. Since Trump’s election, black voters have played a key role in victories by Democratic candidates in Kentucky, Virginia and Louisiana gubernatorial races, and Alabama’s special senatorial election in 2017.

Political scientists Amir Fairdosi and Jon Ragowski found that black Democratic candidates significantly increase turnout of black voters across the ideological spectrum — the candidate’s presence alone is associated with a 5.4 percent increase in turnout probability. Numerous studies, such as one from University of North Carolina professor Christopher Clark and another from Yale University economist Ebonya Washington, show that state black executive and legislative candidates mobilize disengaged black voters, making them 22 percent more likely to vote and raise turnout 2.3 percentage points for every black congressional or gubernatorial Democrat on the ballot.

Recent elections, including 2018, when Gillum and Abrams ran, suggest similar outcomes. Black voter participation rates in presidential elections were at historic highs in 2008 and 2012, when Obama was at the top of the ticket. Further, black female candidates receive even higher levels of support from black women, an especially important bloc given the outsize role of black women in electoral organizing, participation and Democratic support.

The achievable turnout advantage offered by a black running mate may only be on the margins, but that is often where elections are won. Though Clinton received close to 3 million more votes in 2016, Trump’s victory was decided as a result of less than 80,000 votes in Michigan, Pennsylvania and Wisconsin. In these states, the black population centers of Detroit, Philadelphia and Milwaukee are all represented by black legislators.

Past results don’t guarantee increased turnout. Scholarship suggests that the observable increased turnout when black candidates run is more a function of party outreach and mobilization, but that’s not necessarily a hindrance. A black vice-presidential candidate is more likely to prioritize and be more effective at reaching out to black voters, leading to increased turnout — perhaps sufficiently to secure a Democratic victory in those battleground states.

Previous presidential nominees have flirted with the idea of a black running mate. Mondale considered mayors Tom Bradley of Los Angeles and W. Wilson Goode of Philadelphia before choosing Ferraro. The Rev. Jesse Jackson was floated as a running mate in both 1988 and 1992, but his selection was deemed too risky. And Clinton considered both Booker and Patrick to be her running mate in 2016. This time, a black vice-presidential nominee could stir up some of the same racial resentment that helped elect Trump in 2016. And, of course, black candidates aren’t interchangeable — Abrams, Booker, Demings, Harris, Gillum and Patrick each present distinct advantages and risks.

But the lesson from 2016 is that the Democratic Party can’t afford to play it too safe in hopes that the Trump presidency will implode or that partisan and unaffiliated voters will reject Trump en masse. A black vice-presidential candidate can unlock the party’s unique and proven advantage, one that should not be squandered in what looks to be a close election.

More to the point, the Democratic nominee’s chance at winning the election hinges on his ability to mobilize black voters. Based on what is known about catalysts for black voter participation, an active and engaged African American running mate offers the nominee and the party the best chance of getting black voters to the polls in higher numbers, especially in the states that matter most.