With two septuagenarians battling for the nomination and a fervent ideological battle boiling within the Democratic Party, the eventual nominee's vice-presidential pick could have an impact on the general election, according to political scientists and operatives.

Given the diversity of the Democratic Party and its coalition, women and people of color should make up the bulk of both Biden's and Sanders' shortlists, political scientists and operatives told Insider.

The candidate's ideology, regional appeal, and experience will also come into play.

Some pundits and strategists have begun speculating about who the two frontrunners will consider for the job.

One Biden-aligned operative said he'd be "surprised" if Biden's pick wasn't Sen. Kamala Harris.

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With Super Tuesday setting the inescapable delegate math into motion, the Democrats will almost certainly have a septuagenarian white man leading the ticket in November to take on President Donald Trump.

But the other half of that ticket is pretty wide open.

Political scientists and Democratic operatives told Insider that both former Vice President Joe Biden and Sen. Bernie Sanders of Vermont would be smart to look for a younger running mate, preferably a woman or a person of color — or both.

Both candidates have already suggested their future running mates would be women and younger than they are. In December, Biden told a New Hampshire voter he could think of "seven women off the top of my head" who could be his running mate.

Beyond the candidate's identity, their ideology and regional strength will also come into play, and the nominee's goal will be a running mate who offers both balance and broad appeal.

Biden has also said he would pick a running mate who could shoulder significant responsibility and act as almost like an equal partner in the White House.

"Look, the only thing I know a lot about is the vice presidency," Biden said in response to a question about who he would pick for a running mate during a December town hall in Peterborough, New Hampshire. "The responsibility of the president is so immense that no one woman or man can handle the job by themselves. They have to be able to delegate, delegate significant responsibilities — not a joke. And the president did that with me."

Biden said he had enough influence as Obama's vice president that "I could hire and fire. I could pick people throughout the cabinet. I could do exactly as if I were the president, for real."

That codependency, he said, should trump concerns about the running mate complementing the nominee tactically for the general election.

Rep. Val Demings, right. Samuel Corum/Getty Images

Youth, energy, and diversity

Given the diversity of the Democratic Party and its coalition, women and people of color should make up the bulk of both Biden's and Sanders' shortlists, the professors and operatives said.

Ian Russell, a former deputy director of the Democratic Congressional Campaign Committee, said the vice-presidential pick should help energize black and Latino voters as well as college-educated suburban women who came out in force for Democratic House candidates in 2018. And they should be a model for the party going forward.

"It's got to be somebody that the Democratic Party can see its future in," he said.

Russell pointed to Florida Rep. Val Demings, a former Orlando police chief who endorsed Biden on Thursday, as a strong candidate for the former vice president. Another Democratic strategist said either Demings or New Mexico Gov. Michelle Lujan Grisham would make good running mates for Biden. And Axios reported last year that Biden was considering former Georgia gubernatorial candidate Stacey Abrams as his pick.

A Democratic operative working to elect Biden predicted the candidate would choose Sen. Kamala Harris of California, who dropped out of the 2020 race in December, as his running mate. Harris, a former prosecutor and attorney general of her home state, ran on a more progressive platform than Biden but shied away from some of the progressive left's boldest proposals. Harris is considering endorsing Biden, according to The New York Times.

"I'd be surprised if it wasn't Kamala Harris," he told Insider. "I actually think [she] is pretty pragmatic. I think Kamala Harris is closer to Joe Biden's form of politics than she ever was to the stuff she was trying to do on the campaign."

Though Harris was critical of Biden's record on race during the primary, the former vice president praised her when she dropped out of the race.

"Sen. Harris has the capacity to be anything she wants to be," Biden said in December. "I talked to her yesterday. She's solid. She can be the president one day herself. She can be the vice president. She can go on to be a Supreme Court justice."

The operative said Sanders may have a harder time finding a running mate who will have broad appeal and be willing to be branded a democratic socialist. Some have suggested former Ohio state Sen. Nina Turner, a national cochair of Sanders' campaign, or Sen. Tammy Baldwin of Wisconsin, a progressive with a strong track record of wins in a swing state.

"He doesn't want to seem as if he's selling out his people. There is an appearance piece of this, so it's gotta be someone who's going to pass the smell test with his supporters," he said.

Basil Smikle, the former executive director of the New York State Democratic Party, largely agreed.

"For Biden, I imagine black voters who were critical to his resurgence will be looking for an African American running mate," Smikle told Insider. "For Sanders, I think someone that fits his policy profile but may assuage concerns among 'establishment' Dems is possible, though few may fit the model."

But the two Democratic frontrunners find their strongest support in very different segments of the Democratic electorate. While Sanders has a significant lead over Biden among young voters and Latino voters, the former vice president is much more popular than his competitor among older and suburban voters.

Sen. Bernie Sanders with Nina Turner, his campaign's national cochair. Sara D. Davis/Getty

Both candidates will also likely look for a running mate who appeals to the groups they're weak with.

"Vice President Biden needs someone who can help him connect with the youth that Sen. Sanders has energized throughout this campaign," Josh Klemons, a Wisconsin Democratic strategist, told Insider. "Sen. Sanders needs someone who can either help him continue making inroads with communities of color or assuage moderates and conservative democrats that he isn't an ideologue looking to change everything they know about the country."

Historically, the vice-presidential pick doesn't make or break the general election, but there is a danger of picking a running mate who hurts the nominee's chances.

"The percentage of people who said they wouldn't support John McCain in 2008 increased markedly in the immediate aftermath of Sarah Palin's first televised interview," Dan Hopkins, a political-science professor at the University of Pennsylvania, told Insider of the former GOP nominee's choice.

"If they haven't already, I hope that the Biden campaign will start vetting because the most important thing is to do no harm," Russell said.