The search for Joe Biden's running mate has apparently narrowed to six women and at this stage and given the ongoing rage against racism, it seems likely an African-American might emerge as "The One."

Biden pledged to pick a woman as his running mate last March 15 during a debate among Democratic Party presidential contenders. Considering Biden will be the oldest man, at 77, to hold the office of U.S. president when he wins the election on November 3, his choice of vice president is critical due to his age and health.

Sources at the Biden campaign said the process to select the vice president has entered a second round of vetting. It's likely a woman of color will become Biden's running mate given the massive national outcry against racism. Of the six women being seriously vetted as vice president, only one, Sen. Elizabeth Warren of Massachusetts, is white.

Susan Rice, who served as president Barack Obama's national security adviser, is African-American, as is Rep. Val Demings of Florida and Atlanta city Mayor Keisha Lance Bottoms. New Mexico Gov. Michelle Lujan Grisham is a Latina. Sen. Kamala Harris of California is of Indian-Jamaican descent.

Sources in the Biden campaign, however, said the top three are Harris, Warren and Rice. They warned, however, the campaign is still considering other candidates for vetting. And they refused to admit to a top three list, saying this is nothing but early speculation.

"Those who talk don't know and those who know don't talk," said Andrew Bates, a Biden spokesperson.

What can be confirmed, however, is the huge debt of gratitude Biden owes to African-Americans. African-Americans made Biden the Democratic Party nominee.

Biden was in danger of closing down his campaign after humiliating defeats in the first three Democratic primaries. He placed fourth in Iowa on February 3; fifth in New Hampshire and second in Nevada.

The South Carolina primary on February 29 became life-or-death for Biden. Pundits agreed a Biden loss in South Carolina -- a Biden bailiwick because of its huge African-American voting population -- would end his campaign and give the nomination to Sen. Bernie Sanders, an Independent from Vermont.

Biden made a desperate appeal to the black community in South Carolina. Blacks came out in droves to vote for him -- eight in 10 of them did -- giving him the victory in South Carolina. After winning 38% of the vote in South Carolina, Biden won almost all the other primaries and caucuses since. On June 6, Biden officially passed the 1,991 delegate threshold to secure the party's nomination, which will be formalized at the Democratic National Convention (DNC) in August in Wisconsin.

Advisers say Biden's choice is likely to be all about personal chemistry. Former Virginia governor Terry McAuliffe said it will be exciting for the party to have a black woman as the vice presidential nominee.