Vice President Kamala Harris is expected to reveal her running mate on Tuesday morning, a decision that will end a 16-day sprint to vet, interview and choose a person who could potentially become the future leader of the Democratic Party.

Ms. Harris’s announcement, coupled with a major rally she plans to hold with her running mate on Tuesday evening in Philadelphia, will also cap a frenzied period that had, in recent days, exposed some of the party’s internal fissures on matters ranging from labor rights to Israel’s military campaign in Gaza.

With only days to consider a range of contenders, Ms. Harris and her team were inundated with unsolicited advice — much of it public — about whom she should pick. In the final hours, her allies, fellow Democrats, progressive activists and even some of the potential nominees themselves tried to find ways to sway her decision.

At the center of the maelstrom is Ms. Harris, who has fielded input from a small group of formal and informal advisers, including former President Barack Obama, whom she has consulted on policy, personnel decisions and her vice-presidential pick during her whirlwind ascent to the Democratic presidential nomination, according to a person familiar with their conversations.

Some of the candidates even tried to cozy up to influential friends of Ms. Harris’s, hoping that it might make their way back to the vice president — or at least to one of the people in the tight group of confidants advising her. Two presumed favorites, Gov. Josh Shapiro of Pennsylvania and Gov. Tim Walz of Minnesota, have been checking in with Democratic members of Congress by phone in recent days.

Donna Brazile, a former chair of the Democratic National Committee, said she had recently fielded calls from more than one of Ms. Harris’s potential running mates.