Kamala Harris’s choice of a running mate probably won’t decide this year’s presidential campaign. It’s hard to argue that a vice-presidential nominee has swung even a single state over the past 60 years.

Why not? The country’s polarization means that people increasingly base their vote on salient national issues. The media landscape has nationalized, reducing the influence of local news organizations and political parties. And vice presidents receive a fraction of the attention that presidents do.

These factors help explain why Paul Ryan, then a Wisconsin congressman, didn’t help Mitt Romney win that state in 2012 and why John Edwards didn’t help John Kerry win North Carolina in 2004. Not since Lyndon Johnson helped John F. Kennedy narrowly win Texas in 1960 has a running mate arguably made a difference.

But Harris’s choice could still matter very much for other reasons. She will be picking a partner who would help her govern. Most important, she will be elevating a potential future president.

Think back to four years ago. For his running mate, Joe Biden was choosing among Harris, Tammy Duckworth, Susan Rice, Elizabeth Warren, Gretchen Whitmer and a few others. By selecting Harris, Biden effectively chose the 2024 Democratic nominee.

We’ve chatted with our colleagues covering the Harris campaign, and today we offer a breakdown of the leading possibilities. Most analysts expect Harris to pick a white man, as a form of demographic balance, much as Biden picked a woman of color four years ago.