WASHINGTON — Joe Biden’s remarkable comeback from the depths of a fifth-place finish in the New Hampshire primary to all but locking up the Democratic nomination this month can be traced to his overwhelming support among black voters. And one critical endorsement — from South Carolina Rep. Jim Clyburn — helped reinforce that support at a tenuous moment in his candidacy.

As Biden now takes steps to begin formally vetting potential running mate, there are few voices more influential to the former vice president than Clyburn’s. And while there may be pressure from some in the party to not just choose a woman, but an African American woman, Clyburn is more circumspect.

“I think having a woman on the ticket is a must,” the No. 3 House Democrat said in an interview with NBC News. “I’m among those who feel that it would be great for him to select a woman of color. But that is not a must.”

“I think that he should be informed in this decision by the vetting and the polling. And I think he should be guided by his head and his heart,” Clyburn added.

The Biden campaign is expected to announce as soon as this week the team that will help guide him through the vetting and ultimately the selection of his potential vice president. A campaign official noted that Biden "is familiar with the process of selecting a vice presidential candidate, having been on the opposite end of the process in 2008."

“Our campaign will run a vigorous vetting process,” the official told NBC News.

Biden said in an interview with KDKA-TV last week that it’s “very important that my administration look like the nation,” but reiterated that his pledge to choose a black woman for the Supreme Court “doesn’t mean there won’t be a vice president as well.”

The debate about whether Biden needs a diverse ticket is happening not just within Biden’s orbit but throughout the party. And some advocating for it are among those likely to under consideration themselves. Stacey Abrams, who was the party's nominee for governor in 2018, delicately raised her “concern” last week on ABC’s “The View” that Biden’s eventual ticket might not reflect the wishes of the party’s most loyal supporters.

Abrams’ unconventional campaigning for the position, often in multiple national media appearances each day, has raised eyebrows among top Democrats.

“When I am asked a question, I answer it as directly and honestly as I can,” she told NBC's "Meet the Press" on Sunday. “As a young black girl growing up in Mississippi, I learned that if I didn’t speak up for myself, no one else would.”

“I sympathize and I empathize with her,” said Clyburn, who is also black, recalling how when he first ran for House whip, he faced similar skepticism about his qualifications for the post.

He included Abrams, Sen. Kamala Harris, D-Calif., former U.N. Ambassador Susan Rice and Atlanta Mayor Keisha Lance Bottoms as among several qualified women Biden could choose from, but also former opponents for the nomination, like Sens. Elizabeth Warren, D-Mass., and Amy Klobuchar, D-Minn.

Clyburn says he has spoken with Biden several times since the South Carolina primary, most recently on Easter Sunday, April 12, in a call that included Biden’s wife, Jill. He said the conversation was mostly personal, reflecting on the death of Clyburn's wife of 58 years last September.

But Clyburn has shared with Biden’s team a list of preferred selections, according to a source familiar with the interactions between Clyburn and the campaign, and reminded them of how the right African American woman could galvanize the party.

One of the primary arguments for choosing a black woman has been that it could turbo-boost turnout not just to benefit Biden, but down ballot candidates like Alabama Sen. Doug Jones, whose special election victory in 2017 benefited from a spike in turnout from African American women.

Mike Espy, a former agriculture secretary running for the second time for the U.S. Senate in Mississippi, mentioned Abrams, a Mississippi native, as someone who could “make turnout pop” in his state and boost him in November.

“Mississippi has a larger percentage of black voters per capita anywhere in the United States, so we just have to energize them,” he said.

Some are also advocating that Biden choose a Latina to round out the ticket, saying it would provide even more electoral impact. Rep. Tony Cardenas, D-Calif., chairman of the Congressional Hispanic Caucus’ Bold PAC, says he has urged Biden “respectfully” to consider Nevada Sen. Catherine Cortez-Masto and New Mexico Gov. Michelle Lujan Grisham, among others.

“I think whoever he picks is going to be top-notch,” he said, but added that “the Latino voter has a higher propensity of being excited and voting for somebody who is Latino than any other demographic."

"So that’s not something that’s lost on me," Cardenas said.

In a recent poll, Latino Decisions found that only 49 percent of registered Latino voters planned to vote for Biden, but 72 percent said they’d be more likely to turn out if he picked Cortez-Masto.

Biden has been clear about the qualities he considers most important in a potential running mate and governing partner, including being “simpatico” in terms of ideology and someone he can trust to challenge him privately but ultimately lock arms publicly when decisions are made.

But more than anything, Biden has said his vice presidential pick needs to be someone who the public accepts as being ready to assume the duties of the presidency on a moment’s notice — a factor that has only taken on greater import with the country facing an economic and public health crisis.

“People are going to look and say, ‘Is the person Biden picked capable of, God forbid something happened to Biden, that they would be able to take over immediately?’ And so that's the first criteria I look at,” Biden told Iowa voters in January.

Clyburn said he’s been cautioning fellow Democrats about the lesson of the 1972 campaign, when the party’s presidential nominee, George McGovern, had to drop his first VP pick, Thomas Eagleton, after it was revealed that Eagleton had been treated for clinical depression.

“You don’t get a do-over in this,” Clyburn said. “That taught me what hasty decisions do.”

Aides have insisted that Biden has not yet identified a consistent “short list” of favorites. But some of the names most widely discussed among his team and outside allies include black women — Abrams, Harris, Bottoms and Florida Rep. Val Demings.

Harris has stepped up her work as a surrogate for Biden of late, including a lead role in a virtual forum Monday about the impact of the coronavirus on the African American community.

“The recovery process, to get everybody back up on their feet, is going to take some time. We need the right person in the White House to carry us over this bridge. And that's Joe,” she said.

Demings, a member of the House Judiciary and Intelligence Committees and the former Orlando chief of police, said on “AM Joy” this month that she would accept the nomination if offered.

“We have several women who are ready, willing and able, and I just hope and pray that vice president Biden will select an African American woman to serve beside him,” she said.

Asked this week if Biden should choose a woman of color, Michigan Gov. Gretchen Whitmer, herself an apparent contender, said only that she would be “the most enthusiastic supporter of a Biden-Whomever ticket.”

Democrats acknowledge that virtually anyone Biden selects will face questions about his or her readiness to serve as president, even someone like Harris who competed against Biden for the nomination and has won three elections in the nation’s largest state.

Bottoms was asked directly last week whether she believed her two years as mayor of Atlanta was sufficient preparation for the Oval Office.

“After navigating a pandemic and the biggest municipal cyberattack in the history of our country, I think I'm qualified to handle just about anything other than home schooling my four kids,” she told NBC’s Craig Melvin. “I've said all along, I want Joe Biden to win in November. And I trust he will make the best choice that will allow him the best opportunity to take over the White House in November.”