Mr. Biden is said to be focused on finding a running mate he regards as capable of advancing his priorities in governing and who can be counted on not to stray from the urgent challenges facing the nation to pursue their own political priorities, according to people familiar with his thinking. His advisers would also prefer a running mate who would not present a rich political target for President Trump, given that the incumbent is lagging badly in the polls and has so far struggled to deliver credible negative attacks against Mr. Biden. One Democrat close to Mr. Biden's campaign said its polling indicated that Ms. Harris has little allure with Black voters. More telling, a Biden campaign official reached out to The New York Times, unprompted, to say that some of the former vice president's own staff members are not supportive of her.
In conversations with Mr. Biden and his vetting committee, lawmakers have recommended Ms. Bass as a consensus candidate who is well-liked across partisan and factional lines and would be a loyal lieutenant to him in government. Ms. Bass has reinforced that message by assuring Democratic officials that she has no interest in seeking the presidency herself, according to lawmakers directly familiar with the discussions. That commitment could assuage concerns in the Biden camp that he might be overshadowed by a running mate positioning herself to succeed him.