Harris and Warren have been seen as top contenders for the No. 2 spot since ending their own presidential campaigns.

Warren and Biden have forged a surprising bond in recent months and talk regularly about the progressive policy ideas the Massachusetts senator put at the forefront of her campaign. Biden already has adopted her proposed bankruptcy law overhaul. And now, with the coronavirus pandemic and resulting economic slowdown elevating the nuts-and-bolts of governing, some Democrats see Warren’s policy credentials as an asset to the ticket.

A Biden-Warren pairing would mean both Democrats on the ticket are white and in their 70s. Biden is 77, and Warren is 70.

Harris is the lone black contender who has won statewide office, notable experience given Biden’s emphasis on wanting a partner “ready to be president.” She and Biden have also demonstrated a comfortable manner with each other in online fundraisers. Harris is an expert voice in discussions of criminal justice, but some black progressives view her background as a prosecutor skeptically.