"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.