Joe Biden’s confirmation of the biggest open secret in politics — that he would pick a woman as his running mate — was just the start of a thorny selection process that touches not only on gender but race, geography, experience and personal chemistry.

The array of choices in play, according to Biden advisers and allies, reflect the competing forces bearing down on Biden as he looks to the general election. Kamala Harris, Amy Klobuchar and Elizabeth Warren are top names. Michigan Gov. Gretchen Whitmer, Atlanta Mayor Keisha Lance Bottoms and Nevada Sen. Catherine Cortez-Masto are also in the mix.

There’s a powerful current of thought in Democratic circles that Biden needs to choose a black woman after African Americans singlehandedly revived his campaign in South Carolina and the South. But it’s by no means a certainty.