Joe Biden, the presumptive Democratic nominee, will take on Donald Trump in the US presidential election this November.

With the primary contest over, now begins the process to choose another candidate — Biden's running mate.

It's not a decision Biden will make lightly. He'll face questions about being a one-term president if elected, meaning his VP has a good chance of becoming the Democratic nominee in 2024.

Plus, he's considering his age (77 years) and looking for someone "with the ability to lead from day one" in the event of his untimely demise.

Biden has promised his choice will be a woman, so here are five of the most likely to end up on his ticket … and three longshots.

Senator Kamala Harris, one of Joe Biden's potential vice presidential picks ( ABC News )

If you've paid attention to this campaign at all, you might remember this exchange.

Unprompted, Kamala Harris delivered a fierce jab in the first primary debate, sending her stocks skyrocketing in the presidential race. Her move had pundits asking if Joe Biden could really survive a bruising campaign.

But Harris's popularity came back to earth, then cratered. Joe Biden did survive, and won.

All's fair in love, war and politics, and Harris has already hit the campaign trail for the candidate she once threw under the rhetorical bus.

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With her career as an attorney-general and some uncompromising Senate hearings under her belt, Harris is well suited for the first job of any VP pick — putting the opponent on blast — but also has the Capitol Hill experience to back it up if/when the pair make it to the White House.

What makes her a good pick? She's a mixed-race American, a sitting US senator and only 55 years old. Her presidential campaign pitch — I'm everything Joe Biden isn't — is what makes her the almost-perfect candidate to balance the Democratic presidential ticket.

Why might Biden look elsewhere? Harris wouldn't be Biden's first choice if his VP pick is a move to appeal to the young progressives that fuelled the Bernie Sanders campaign. And you best believe that the attack on Biden in the debate will be recycled into an ad by the Trump campaign.

Stacey Abrams, one of Joe Biden's potential vice presidential candidates. ( ABC News )

Stacey Abrams narrowly lost the gubernatorial race in Georgia in 2018, but the tight contest catapulted her into the national spotlight and onto a million lists like these.

She delivered the 2019 Democratic State of the Union response, a speech given by plenty who have gone on to occupy the Oval Office in their own right.

A fierce advocate for voting rights (not least because of the circumstances that led to that 2018 loss), Abrams would be a powerful ally to have in an election that is already looking like it will need to rely on mail-in ballots because of the coronavirus pandemic.

After resisting overtures to run for president or the Senate in 2020 herself, Abrams has been explicit in her desire to be considered for the VP ticket.

Plus, there are no hatchets to bury here. The rising star of the Democratic party has spoken fondly of Biden, saying the pair had a "lovely lunch" in 2019 well before the former vice-president got in the race.

What makes her a good pick? Hailing from Georgia, Abrams could be the tipping point in a state that is looking pivotal in the Electoral College. And after the majority of Democratic voters picked a candidate who promised a return to the past to defeat an opponent in the present, choosing Abrams would send an olive branch to Democrats looking to the future of the party instead.

Why might Biden look elsewhere? Abrams's youth is a double-edged sword; her only electoral experience so far is 10 years in a state House of Representatives. It's not nothing (Donald Trump held no elected office after all), but the presidential campaign stage is typically reserved for US senators and state governors.

Governor Gretchen Whitmer, one of Joe Biden's potential vice president picks ( ABC News )

Gretchen Whitmer was one of hundreds of Democratic women inspired to run in the wake of Trump's victory.

She successfully flipped a Republican seat during the 2018 midterms, and now serves as the Governor of Michigan. Her pragmatic, moderate approach is likely to help the Democrats win back a mid-western state that took the party by surprise by backing Trump in 2016.

She's one of the newest rising stars in the Democratic party (and a lightning rod of Republican criticism). She gained even more name recognition by delivering the State of the Union response earlier this year.

Whitmer told reporters "it's not going to be me" when it comes to the VP pick, but that was before she became a standout for state-level coronavirus leadership. She recently appeared on Biden's campaign podcast, where the two displayed a genuinely strong rapport.

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What makes her a good pick? At age 48, Whitmer is on the younger side for US politicians, and has already proven she can appeal to voters of both parties. Plus, if coronavirus is still front of mind for voters come November (which is looking likely), she'll have plenty of firsthand stories about Trump's missteps.

Why might Biden look elsewhere? Her middle-of-the-road approach doesn't do much to diversify the ticket ideologically. There's also the national party strategy to consider: Whitmer only narrowly won the key governor's seat and removing her prematurely might cause it to flip back.

Senator Amy Klobuchar, one of Joe Biden's potential vice president picks ( ABC News )

Biden's path to victory runs straight through the midwest, and that's where Amy Klobuchar shines.

The Senator from Minnesota wins in even ruby red districts and, as a 2020 candidate, showed promise in polls around battleground regions. Despite never finishing higher than third in primary contests, her debate-stage zingers helped establish strong name recognition with the American public.

She's known for her folksy puns and working-class roots, but, importantly, she's able to back up the charm with a formidable 14-year congressional record. She's worked closely on things like healthcare and immigration, two issues that are top of the Democrats' list.

What makes her a good pick? She's ideologically similar to Biden, but still holds sway over the moderate vote. When she dropped out to endorse Biden ahead of Super Tuesday, her home state of Minnesota voted for him in droves. There's plenty of reason to believe that influence would stretch over other key swing states in the region like Wisconsin and Michigan.

Why might Biden look elsewhere? Two liabilities surfaced on the campaign trail: She doesn't perform well with minority voters, and there's some embarrassing stories of her mistreating her staff. More may be out there.

Catherine Cortez Masto, one of Joe Biden's potential VP picks ( ABC News )

One of Biden's most eye-opening primary losses came in Nevada, where Bernie Sanders swept the Hispanic vote. California and Colorado went to Sanders for the same reasons.

Hence why the Senator from Nevada is being eyed as a VP pick. Catherine Cortez Masto was the first Latina ever elected to the US Senate and has made immigration her top issue. Since stepping in as a Senator in 2017, she's served on key committees including Finance and Energy.

She also has experience as the state's attorney-general and proved her ability to work across party lines to pass legislation on issues like human trafficking.

Cortez Masto comes with some serious fundraising chops and has the support of high-ranking figures in the party like former Senator Harry Reid.

One thing to note though: She's yet to formally endorse Biden's campaign.

What makes her a good pick? Cortez Masto could help Biden win over western states thanks to support from Hispanic voters. Should nationwide vote-by-mail become a reality this November, turnout among this group is predicted to be higher than ever so it's critical they stick with the Democrats.

Why might Biden look elsewhere? With only three years in congress under her belt, Cortez Masto lacks the experience — as well as the name recognition — that others bring to the table.



The longshots

Tammy Duckworth, Elizabeth Warren and Andrew Cuomo would be surprising yet logical VP choices. ( Reuters )

Elizabeth Warren: A Senator with almost a decade of experience in Washington, boasting progressive enthusiasm that manifested in hours-long lines for selfies and the national campaign experience Biden's team said they're after is … a longshot?

Yep. It's because of something a lot simpler than US electoral politics. Biden and Warren simply don't like each other very much.

It's a feud that goes back decades and is seeded in the issue that drove Warren to pursue a political career — bankruptcy reform.

If the two are prepared to work together on a ticket, it won't be so much a hatchet as a medieval broadsword worth of baggage that they'll need to bury.

Tammy Duckworth: You've probably not heard of Tammy Duckworth, but she's a politician with a bevy of "firsts" to her name including:

The first person born in Thailand elected to Congress

The first person born in Thailand elected to Congress The first female double-amputee elected to Congress (she lost both legs in the Iraq War when the helicopter she was piloting was hit by an RPG)

The first female double-amputee elected to Congress (she lost both legs in the Iraq War when the helicopter she was piloting was hit by an RPG) The first woman Senator to give birth while in office

Duckworth has served both as a member of the House of Representatives and now as a Senator from Illinois, and as a moderate she fits neatly into the ideology of the Biden campaign.

The Purple Heart recipient is just lacking the kind of national profile of other names on the list, but her resume more than makes up for her lack of star power.

Andrew Cuomo: Before you ask, we know that Governor Andrew Cuomo isn't a woman. But we're talking about longshots here.

It's going to take something monumental for Joe Biden to go back on his pledge to choose a woman as a VP candidate, but successfully guiding New York out of the coronavirus crisis could be big enough.

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The Governor has been on the national and international stage as he's grappled with the crisis gripping the state, and his constituents have overwhelmingly approved of his work.

In a Siena College poll, 87 per cent of New Yorkers approved of the job he was doing, including 70 per cent of Republicans. That's almost unheard of in an America divided by partisanship.

If the coronavirus pandemic in the US doesn't improve, picking the man who helped guide New York out of the abyss to lead a national response could be tempting for Biden — even if it means going back on an earlier promise.