WASHINGTON — Joseph R. Biden Jr. has entered the final stage of his deliberations about choosing a running mate as he prepares to talk one-on-one with the finalists next week, while Democratic leaders lobby him furiously to elevate their allies and sink their enemies.
Mr. Biden’s campaign has conducted extensive polling and focus groups with voters on a collection of candidates and weighed an array of factors, such as the impact of the pick in battleground states, and whether to choose a Black woman. Aides say the announcement will come the week before the Democratic convention in August.
Two candidates who received scant attention early in the process are now among the leading contenders: Representative Karen Bass of California and Susan E. Rice, the former national security adviser, according to Democratic officials briefed on the selection process. Ms. Bass in particular has moved rapidly toward the top of Mr. Biden’s list amid an intensive lobbying drive by her fellow House Democrats, and has impressed the former vice-president’s search committee.
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.
James E. Clyburn, the third-ranking House Democrat who helped revive Mr. Biden’s campaign in South Carolina, said he had been bombarded by supporters of several candidates.
“I’ve heard from the surrogates of about all the people in the race,” said Mr. Clyburn, who did not rule out making a late, private recommendation to Mr. Biden.
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.
Ms. Bass has also waged a previously undisclosed campaign to woo influential liberal leaders, telephoning union presidents to seek their counsel and support.
House Speaker Nancy Pelosi is close with Ms. Bass, whom she named to oversee the recent policing reform bill, and has made her admiration clear in private conversations, including with former President Barack Obama. Ms. Pelosi’s aides said she has not conveyed support for any one candidate, is fond of a number of them and, in speaking with Mr. Biden’s vetting team last month, urged them to find somebody who could ensure the ticket is victorious.
Two prominent Democrats, Senators Elizabeth Warren of Massachusetts and Kamala Harris of California, along with a handful of other women, remain as possibilities; both lawmakers have the statewide political experience and large national followings that Ms. Bass and Ms. Rice lack. Ms. Warren has become something of an informal adviser to Mr. Biden on economic issues and has won support from her party’s progressive wing, and Ms. Harris is regarded as a muscular fund-raiser with the backing of important people in the Democratic Party’s donor class.
While Mr. Biden’s advisers are careful to stress that he has not ruled out any of the major candidates, some are clearly less likely than others to be chosen. For some of the long-shot candidates, talk has already turned to other potential roles in a Biden administration: Gov. Michelle Lujan Grisham of New Mexico, for instance, has expressed interest in the job of health and human services secretary, according to officials familiar with her thinking.
Among the other candidates Mr. Biden has looked at closely are Gov. Gretchen Whitmer of Michigan; Representative Val Demings of Florida, who has enlisted her home state’s sizable congressional delegation to make appeals on her behalf; and Senator Tammy Duckworth of Illinois, who is backed by veterans advocates.
Gov. J.B. Pritzker of Illinois has called Mr. Biden’s team to urge them to put Ms. Duckworth, a military veteran, on the ticket. Senator Jack Reed of Rhode Island, the top Democrat on the Senate Armed Services Committee, has shared his high opinion of Ms. Duckworth with the Biden camp, and also urged them to pick his home-state governor, Gina Raimondo, people familiar with the conversations said. However, Mr. Biden’s vetting committee has raised questions about whether tapping Ms. Duckworth could prompt legal challenges because she was born overseas.
There also some wild cards: Former President Bill Clinton has expressed enthusiasm about Atlanta Mayor Keisha Lance Bottoms, according to Democrats familiar with his assessment.
The former vice president’s decision has become both enormously consequential and highly delicate because of the unresolved question of whether, should he win in November, he would seek re-election in four years, when he would be nearly 82 years old. With his selection, Mr. Biden may be effectively coronating the next Democratic presidential nominee and charting the party’s course for the next decade.
This is why some progressives are hoping he balances the ticket by picking a more liberal running mate.
“It shouldn’t be someone that just amplifies what Biden does well,” said Representative Alexandria Ocasio-Cortez of New York. “It should be somebody that brings new constituencies to the table.”
Some of his top advisers, however, are warning against tapping somebody who would immediately begin eyeing the next Democratic primary.
“There’s going to be an awful lot to do starting on Day 1, so I think it’s important to have somebody who can be focused on that task and not running for president as soon as we finish the inauguration,” said Representative Cedric Richmond of Louisiana, one of Mr. Biden’s campaign chairs.
Mr. Biden’s top aides have made clear the premium he places on a trusting relationship is informed by his own experience as a vice president — and he will not make a nakedly political choice, a determination made easier by the sizable advantage he enjoys over Mr. Trump in the polls.
“The Bidens are looking for somebody as loyal to them as they were to Barack and Michelle Obama,” said Christine Pelosi, the daughter of the speaker.
Mr. Biden’s campaign is angry about a leak to Politico this week that revealed that former Senator Christopher J. Dodd, one of the leaders of Mr. Biden’s search team, is uneasy with Ms. Harris. Mr. Dodd has repeatedly indicated to allies that he believed Mr. Biden should broaden the prospects and not focus on only well-known possibilities.
Mr. Dodd is scarcely alone in his lack of enthusiasm for Ms. Harris, whose own presidential campaign never matched its high expectations; she dropped out two months before voting began.
“The thing I keep thinking about Kamala is her performance in the primary,” said Representative Filemon Vela of Texas, an early supporter of Mr. Biden. Mr. Vela said his top three choices were Ms. Bass, Ms. Rice and Ms. Duckworth — but he said the last two would fare best in his state.
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.
California Democrats, including several in Congress, have expressed their wariness about Ms. Harris to Mr. Biden’s advisers. In some cases, they have guided him in the direction of Ms. Bass, who is highly regarded in her home state.
David Crane, a Democrat and former top adviser to Arnold Schwarzenegger when he was governor of California, said he had reached out to Mr. Biden’s camp to tell them Ms. Bass was “a good person who cares about legislation.” He said he conveyed his belief that she would be a far better partner for Mr. Biden than Ms. Harris, who he said did not “walk her talk” on policy.
“They’ve got to pick somebody who really knows how to govern,” Mr. Crane said, stressing what he described as Ms. Bass’s gift for steering complex legislation. “Karen Bass knows how to do that. Kamala Harris has never been in that position.”
Ms. Harris addressed the criticism she is receiving on Friday during a livestream conversation for the Black Women Lead 2020 conference. “There will be a resistance to your ambition,’’ adding that the people resisting are “burdened by only having the capacity to see what has always been instead of what can be.’’
And Ms. Harris does have allies.
“You only need to look at her record at the local, state and federal levels to know that she’d be a quality, experienced partner who’s ready to lead on Day 1,” said Rusty Hicks, who also praised Ms. Bass and is neutral in his capacity as chair of the California Democratic Party.
While Ms. Rice has a close relationship with Mr. Biden, many in the party are wary of elevating somebody who has never run for office.
Ms. Bass, too, has drawbacks. She has never been in a setting comparable to a high-stakes debate with Vice President Mike Pence. And in private vetting conversations, members of Mr. Biden’s team have asked Ms. Bass to explain aspects of her record on Cuba: She visited the country multiple times in the Fidel Castro era and issued a respectful statement when he died. Ms. Bass has said publicly that she had reconsidered those comments.
Clearly, though, Mr. Biden is facing the most intense lobbying to choose a Black running mate.
A small group of strategists and activists who have been pressing for a Black woman recently spoke with members of the search committee, according to two people with knowledge of the conversation. They discussed the electoral map and how the political environment in the country had shifted following the killing of George Floyd in police custody in May.
When given the opportunity to make a case for a specific candidate, participants indicated their support of any of the Black women considered, but Ms. Harris and Ms. Rice came up the most, the people familiar with the conversation said. They noted that the meeting unfolded before it was evident how seriously Ms. Bass was being considered.
In the House, several Democratic lawmakers have made the case for Ms. Bass to Mr. Biden’s advisers.
Representative Josh Gottheimer of New Jersey, a centrist leader of the bipartisan Problem Solvers Caucus, called Ms. Bass “a bridge-builder,” who “wants to figure out how to get to yes.”
Representative Ro Khanna of California, an outspoken progressive, was equally succinct: “She’d be a pick that every part of the Democratic coalition would respect and be excited about.”