Just like that, it’s over. Now that Vermont Senator Bernie Sanders has dropped out of the Democratic primary, former Vice President Joe Biden begins the march towards his coronation in Milwaukee (maybe) in August as the Democrats’ nominee for president. A major step in that march is the selection of a vice presidential running mate; someone who can unify the party, perhaps provide additional competitiveness to the ticket, and drive turnout for and inspire confidence in the 77-year-old Joe Biden. We’ve talked about when we’d expect this announcement to be made, and though it’s likely months away based on what we can infer from history, we also laid out the case for why you might expect this announcement to come sooner. Either way, we know our nominee, and we’ve spent months tracking the strongest vice presidential picks for Biden. 

Biden announced during the last Democratic debate that his running mate would be a woman, and though it’s not likely he will break that promise, this is a good place to stress that the tracker finds the strongest potential matchups regardless of Biden’s statements. Even though Biden has said a woman will be his running mate, our list will still include some men because they are calculated to be stronger running mates with Biden than a generic woman. We already have a built in metric to increase the score for ticket diversity (both in race and gender) based on a regression performed on the corresponding change in betting odds when the Democratic nominee is a woman against the odds of the Democratic vice presidential nominee being a woman. This estimates that gender diversity is important for 20% of the value of the ticket. But the vice presidency is not and should not be a tokenizing position, and if a man is truly a more compatible running mate than a woman, the tracker’s job is to show that and show why this particular ticket is strongest.

The goal of the tracker is to find the strongest ticket given the nominee, not to predict a running mate. Finding the strongest matchups is nonetheless a good proxy for probability (if a campaign is acting in its rational best interest), and our more rigorous historical data-based and algorithmic tracker has nonetheless fallen in line with many other sites’ predictions for likely vice presidential picks. Still, because of the strict algorithm, you may note that the tracker has been bearish on oft-mentioned potential VPs like Massachusetts Senator Elizabeth Warren (who is from a noncompetitive state),Our tracker is not specifically dinging her for this because Massachusetts is so uncompetitive (though it is dinging folks from more competitive states like Ohio Senator Sherrod Brown and Arizona Senator Kyrsten Sinema), but Warren also represents a Senate seat that a Republican governor would have the power to temporarily fill, something Democrats are not likely to want in an election where the Senate is in play. Florida Representative Val Demmings (who is a two term congresswoman and does not meet our “minimum viable office” threshold) or former Georgia State House Minority Leader Stacey Abrams (who also does not meet the minimum viable office threshold).

With all of that in mind and with the knowledge that these are Biden’s strongest choices, let’s take a look at the top ten contenders as of Sanders’ withdrawal.All scores are as of April 8, and are liable to move around a bit as the generic ballot adjusts. The generic ballot was at a -7.7 lean (negative indicating towards a generic Democrat) at the time of the data pull.

#10 – Oregon Governor Kate Brown (Score: 36.28)

Strengths: geography, state experience, gender diversity
Weaknesses: experience match, noncompetitive state

Brown may be the least floated name in our top ten and she has not received much — if any — speculation for the pick, despite the fact that she has thirty years of state experience in Oregon, is a prominent female governor from the West, and the first openly bisexual person elected governor in the history of the United States. Brown would be a gesture towards an area of the country that Democrats are very strong but often ignore (more picks from the West will round out our top five), and for women’s and LGBTQ advocacy in general. With a strong environmental and public health record, the fact that Brown’s name does not come up more frequently seems like a mistake.

#9 – Former Massachusetts Governor Deval Patrick (Score: 37.54)

Strengths: geography, state experience, race diversity, doesn’t hold an office (not a key seat)
Weaknesses: gender diversity, noncompetitive state

Very briefly in the race himself, the New Englander holds the benefit of geographic diversity from Biden and eight years of state experience, which balances nicely against Biden’s largely federal experience. Patrick was a civil rights lawyer at the Department of Justice and the first African-American elected governor of Massachusetts. Many in the Obama sphere (the former President and Patrick are longtime friends and allies) would appreciate this gesture, and even view Patrick as a more obvious “natural heir” to Obama’s legacy than Biden.

#8 – New Hampshire Senator Maggie Hassan (Score: 38.32)

Strengths: geography, gender diversity, experience match, competitive state
Weaknesses: key seat risk

Hassan is a relatively new member of the Senate, coming to office in 2017 after serving two terms as New Hampshire’s governor. Another New Englander with a strong experience balance with Biden, Hassan benefits from New Hampshire’s competitiveness, but despite the strong Democratic lean heading into the election she’s knocked down in the rankings because her seat is more likely to be filled by a Republican than some of the other potential VP picks. This is fair, considering she won election in 2016 by under 1,000 votes; that same year, New Hampshire was the state that Hillary Clinton won by the smallest margin.

#7 – Minnesota Senator Amy Klobuchar (Score: 39.38)

Strengths: geography, gender diversity
Weaknesses: experience match

Klobuchar’s name has come up frequently as a likely Biden VP pick, with commentators stressing her electability. Though she ran in the primaries as a moderate alternative to Biden and managed to stay in longer than many of her colleagues, she nevertheless bowed out and endorsed him before Super Tuesday. Klobuchar hails from a region that Democrats believe is key in unseating Trump and has already exceeded electoral expectations in Minnesota, overperforming the state’s partisan lean by 22 points in her 2018 election. Though she’s not a newcomer to the Senate, she hasn’t been there for decades like Biden has, and she has state prosecutor experience to round out her outsider credentials. Klobuchar makes sense as a safe, inoffensive pick who can run on a platform of pragmatism and competency, as well as a geographically competitive pick, and — though our tracker does not use this as a metric — an ideologically similar pick to the moderate Biden.

#6 – Former Secretary of Housing and Urban Development Julian Castro (Score: 41.83)

Strengths: race diversity, geographic diversity, doesn’t hold an office (not a key seat), experience match
Weaknesses: gender diversity

Castro ran in the primary as well before endorsing Elizabeth Warren, and though a Warren-Castro ticket makes a lot more sense mathematically (score: 60.94), the same qualities that made him a strong contender for Hillary Clinton’s VP also make him an appealing pick for Biden. Castro, a former Obama cabinet official from Texas, has nearly a decade of experience in San Antonio politics, which complements Biden’s weaknesses in Southwestern appeal and local experience nicely. Though he may be a bit left leaning for Biden, his youth, energy, and appeal among Latinx voters will be key to in helping Biden win Southwestern states and fight Trump on his home turf in Florida. Biden’s top five strongest VP picks however include several more competitive and ideologically compatible Latina women, so Castro will likely be passed over once more.

#5 – Hawaii Senator Mazie Hirono (Score: 44.83)

Strengths: geography, gender and race diversity, not a key seat
Weaknesses: experience match, noncompetitive state

Hirono has also been near the top of our list for a long time despite her strong vice presidential credentials receiving very little press attention. This is probably because of her age. She will turn 73 on the day of the 2020 election, which our tracker does indirectly knock her down for based on her and Biden’s federal cumulative “over-experience”. The senator from Hawaii does have 22 years of state experience that pick up her numbers relative to other generic picks, and her diversity and (extreme) geographic disparity pick up her numbers as well. She was a vocal player during Brett Kavanugh’s confirmation hearing, one of the most memorable and energizing events of the Trump presidency, and has been a strong proponent for women’s issues and the #MeToo movement, which would both make for a strong foil to the Republican ticket and lend Biden some credibility with these issues.

#4 – New Mexico Governor Michelle Lujan Grisham (Score: 50.04)

Strengths: geography, gender and race diversity, not a key seat
Weaknesses: experience match

The only female governor of color, Lujan Grisham is a strong contender in part because she is the only non-senator in the top five. In a year where Democrats are anxious to make the battle for the Senate as competitive as possible, the New Mexico governor may be a perfect compromise in terms of electability, diversity, and security. As a Latina from the Southwest and a former chair of the Congressional Hispanic Caucus, she is a strong demographic complement to Biden even though she falls a little short from an experience standpoint since she’s only been a governor for two years. Expect to hear more about Lujan Grisham — she’s a dark horse candidate to be sure, but one who would allow Biden to garner credibility with the border states thrust into the spotlight under the Trump administration and perhaps broaden the Democratic coalition in competitive states with large Latino populations like Arizona, Nevada, Colorado, and even Texas.

#3 – Illinois Senator Tammy Duckworth (Score: 50.87)

Strengths: geography, gender and race diversity, not a key seat
Weaknesses: noncompetitive state

Duckworth actually does a lot better in our tracker that you might expect, given the noncompetitiveness of Illinois in national elections and that her experience compatibility with Biden is a bit short of where contemporaries like Catherine Cortez Masto and Kamala Harris fall. The tracker gives her a boost because of diversity and her Senate seat not being easy to lose, but it’s not difficult to see why she’d appeal outside of our algorithm. An Iraq War veteran who lost her legs when her helicopter was shot down, she requested and received a waiver to continue serving after her double amputation. She then ran for public office and became the first woman with a disability to be elected to Congress, the first senator to give birth in office, and has been a prominent advocate for veterans within the party and the chamber. Duckworth can speak with experience on military and veterans issues, has maintained a moderate record, and represents many communities and constituencies in the country that Biden does not strongly resonate with on his own.

#2 – Nevada Senator Catherine Cortez Masto (Score: 52.65)

Strengths: geography, experience match, gender and race diversity, competitive state
Weaknesses: key seat risk

I am actually incredibly proud that our tracker has consistently presented Nevada Senator Catherine Cortez Masto as a top choice for Biden. Throughout all of February (even with a major caucus in her home state) she was not making major news as a potential VP pick. Nowadays, her name has broken into the headlines, and there are rumors that she’s one of Biden’s top three choices. Cortez Masto makes sense mathematically as well as pragmatically: Nevada is a close state, but still Democratic-leaning enough that the risk of her seat being filled by a Republican isn’t too high. She served as the state’s Attorney General for eight years before being elected to retiring Senate Minority Leader Harry Reid’s seat in 2016; and not only is she a prominent Democrat in the Senate (she currently serves as Chair of the Democratic Senatorial Campaign Committee), but she is the first Latina ever elected to the chamber.

Even though Nevada only has six electoral votes, she still gets a larger boost from the competitiveness of her state than any other top ten pick. Nevada is also an important state for Democrats symbolically this year, as it is a labor union stronghold and will be one of, if not the, most affected state by the novel coronavirus crisis due to its heavy reliance on the service and hospitality industries. Definitely keep an eye on Cortez Masto.

#1 – California Senator Kamala Harris (Score: 59.44)

Strengths: geography, experience match, gender and race diversity, not a key seat
Weaknesses: noncompetitive state

Finally we get to a choice that  has seemed so obvious that it’s become almost boring. Despite their infamous face off in one of the Democratic presidential debates, Harris has been floated as a running mate for Biden for nearly a year, and for good reason. She, like Cortez Masto, was Attorney General in her home state before being elected to the Senate in 2016, has a strong balance of state and federal experience, and possesses the geographic and demographic diversity that Biden lacks. Biden has even gone out of his way to tease the speculators with his outreach to Harris and Harris herself seems to be making moves typical of a national nominee. 

Despite the misguided loftiness of her presidential campaign, Harris is clearly a rising star in the party who captures a midpoint between its more moderate, establishment members and the left. It would be wise for a forward-thinking Biden campaign and Democratic Party to give her a stepping stone as a party leader. Our exemplars at FiveThirtyEight have noted these strong benefits for Harris and concluded that “Biden is a party man, and Harris is a party choice.” And, holding no grudge of his own from the primaries and apparently eager to elevate other Democrats on his way to the presidency, Biden would be well served to build his party’s future, acknowledging that he will not be its standard bearer for long.

The fact that she represents the largest state in the country and that her seat is safely in Democratic hands makes Harris an ideal choice for the first Western politician to be nominated on a Democratic presidential ticket. A Biden-Harris ticket would be cross-country, diverse, and woman forward, uniquely uniting the Democrats and firing them up for the showdown they’re anxious for this autumn.