Behind Kamala Harris’s Rise: Silicon Valley’s Wealthiest Woman

After Vice President Joe Biden swore in Kamala Harris as a United States senator in January 2017, they posed for a customary photo in the Capitol with her family. Then she asked her future boss for a favor: Would he indulge in one more photo?

“Come on, everybody,” Ms. Harris said, waving in a dozen others. “My extended family is here.”

The first member of Ms. Harris’s entourage to approach Mr. Biden just happened to be one of the richest people in the world: Laurene Powell Jobs.

Ms. Powell Jobs, the philanthropist who controls a fortune worth over $11 billion, stood just behind Mr. Biden’s right shoulder, joining Ms. Harris’s best friend from kindergarten and others in her inner circle. As the photo was snapped and the group broke up, Mr. Biden grabbed a coveted 60 seconds with Ms. Powell Jobs — asking about her son and talking about his ambitions for cancer research.

Few figures have cultivated a more consequential friendship with Ms. Harris, now the Democratic nominee for president, than Ms. Powell Jobs, who for decades was married to one of America’s most famous entrepreneurs, Steve Jobs.

Over the past 20 years, she has become one of Ms. Harris’s most essential confidantes, providing counsel and money, and helping to expand Ms. Harris’s public profile. Now, in this year’s presidential race, the wealthiest woman in Silicon Valley has emerged as a powerful player behind the scenes. She has quietly contributed millions of dollars to an organization backing Ms. Harris, according to three people briefed on the gifts.

She played a hidden but key role in helping usher Mr. Biden out of the race, which cleared the way for a Harris run.