WASHINGTON (NYTIMES) - Joe Biden 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.

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 said 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: Rep. Karen Bass of California and Susan Rice, the former national security adviser, according to Democratic officials briefed on the selection process.

Bass in particular has moved rapidly toward the top of Biden's list amid an intensive lobbying drive by her fellow House Democrats and has impressed the former vice-president's search committee.

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 Donald Trump, given that the incumbent is lagging badly in the polls and has so far struggled to deliver credible negative attacks against Biden.

In conversations with Biden and his vetting committee, lawmakers have recommended Bass as a consensus candidate who is well-liked across partisan and factional lines and would be a loyal lieutenant to him in government.

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.

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 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.

Pelosi's aides said she has not conveyed support for any one candidate, is fond of a number of them and, in speaking with 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 Bass and Rice lack.

Warren has become something of an informal adviser to Biden on economic issues and has won support from her party's progressive wing, and Harris is regarded as a muscular fundraiser with the backing of important people in the Democratic Party's donor class.

While 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 Biden has looked at closely are Gov. Gretchen Whitmer of Michigan; Rep. Val Demings of Florida, who has enlisted her home state's sizable congressional delegation to make appeals on her behalf; and Sen. Tammy Duckworth of Illinois, who is backed by veterans advocates.

Gov. J.B. Pritzker of Illinois has called Biden's team to urge them to put Duckworth, a military veteran, on the ticket; and Sen. Jack Reed of Rhode Island, the top Democrat on the Senate Armed Services Committee, has shared his high opinion of Duckworth with the Biden camp, and also urged them to pick his home-state governor, Gina Raimondo, people familiar with the conversations said.

However, Biden's vetting committee has raised questions about whether choosing Duckworth could prompt legal challenges because she was born overseas.

There also some wild cards: Former President Bill Clinton has expressed enthusiasm about Mayor Keisha Lance Bottoms of Atlanta, 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 reelection in four years, when he would be nearly 82 years old. With his selection, Biden may be effectively coronating the next Democratic presidential nominee and charting the party's course for the next decade.

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 Rep. Cedric Richmond of Louisiana, one of Biden's campaign chairs.

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 Trump in the polls.

While Rice has a close relationship with Biden, many in the party are wary of elevating somebody who has never run for office.

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 Biden's team have asked 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. Bass has said publicly that she had reconsidered those comments.

Clearly, though, 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 Harris and Rice came up the most, the people familiar with the conversation said. They noted that the meeting unfolded before it was evident how seriously Bass was being considered.

In the House, several Democratic lawmakers have made the case for Bass to Biden's advisers.

Rep. Josh Gottheimer of New Jersey, a centrist leader of the bipartisan Problem Solvers Caucus, called Bass "a bridge-builder" who "wants to figure out how to get to yes." Rep. 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."