Harris adds to a diverse workforce where a majority, like their boss, are women of color

While Ms Flournoy’s appointment has been seen as ensuring that a grown person will be in charge of Ms Harris’s office, she is not without critics, who said she doesn’t always have the right instincts to protect Ms Clinton politically damaging times.

Many assistants in Ms. Clinton’s orbit hold Ms. Flournoy responsible for Mr. Clinton’s ill-fated reunion on the airport tarmac with Loretta E. Lynch in June 2016 when Ms. Lynch was Attorney General and the FBI was reviewing the circumstances around Mrs. Clinton’s use of a private mail server during her tenure as Secretary of State.

Mr Clinton was ending a sweltering day on the election track in Phoenix to support his wife’s presidential run when the Secret Service alerted Ms Flournoy and other staff that Ms Lynch’s government plane was parked next to his . Ms Flournoy said the former president, often eager to reunite with friends, acquaintances and even political rivals, would like to say hello to Ms Lynch, according to a person familiar with the events.

Ms Lynch, who had a foot injury at the time, invited Mr Clinton to board his plane to escape the heat, and Ms Flournoy did not stop him from boarding alone, explaining that he and the prosecutor general should have some privacy.

When the meeting became known, it sparked a storm of Republican criticism and Ms Lynch ended up recusing herself from overseeing the email investigation, announcing instead that she was relying on the FBI who set the stage for James B. Comey, the office manager, to make a public statement sharply criticizing Ms. Clinton even though he announced that she would not be charged.

Angel Ureña, a spokesperson for Mr Clinton, disputed that Ms Flournoy was in any way responsible for the incident on the tarmac and said she had the support of those working with her.

“I’ve been working for Tina for almost eight years, so I’m in a pretty good position to say where my colleagues and I are, what’s behind her,” Ureña said. “We love and respect her, she will be missed and have absolutely no doubt that she will be just an asset to the Vice President-elect and the country.