Vice President Kamala Harris didn’t appear at her watch party as it neared 1 a.m. Eastern time Wednesday as her path to victory shrunk, prompting her campaign chief to say she will instead address supporters later in the morning.

“You won’t hear from the vice president tonight,” Harris campaign chair Cedric Richmond told the crowd gathered at Howard University, her alma mater.

Mr. Richmond said Ms. Harris will return later Wednesday and address the audience at the D.C. university and “the nation.”

“Thank you for believing in the promise of America,” he said. “We still have votes to count. We still have the states that have not been called yet. We will continue overnight.”

At the time he spoke, two of the seven swing states had been called for former President Donald Trump — North Carolina and Georgia — and he was leading in all four of the others that had done significant vote counting.

Mathematically, Ms. Harris would almost have to perform a clean sweep of those states.

Mr. Richmond pledged that the campaign will continue to “monitor the vote.”

The appearance of Mr. Richmond to address the crowd immediately drew comparisons to 2016, when Hillary Clinton sent campaign chairman John Podesta to address the crowd at her watch party ahead of her election defeat.

“The entire girl boss ‘I’m speaking’ campaign send a man out to speak for her on election night. Perfection,” wrote Trump adviser Stephen Miller on Twitter.

Roughly half the crowd gathered to watch the election results at the watch party left after midnight without a visit from the vice president as Ms. Harris’ path to victory became narrower.

The crowd was cheering, dancing and listening to loud music all night, but became immediately silent after North Carolina was called for Mr. Trump.

“I wasn’t scared when I came here tonight, but I’m scared now,” Malika Washington, 24, a Harris supporter from the District, told The Washington Times as she left the watch party.

A Howard University student, who declined to give her name, said she was going home and planned to watch the rest of the results there.

Both left before Ms. Harris, who was scheduled to speak, arrived at the watch party. Ms. Harris was expected to depart for the watch party around 10 p.m. Reporters traveling with Ms. Harris said at 10:18 EST that they were holding at her residence and had “no further guidance.”

Revelers had gathered at the Yard, a large open space on Howard University’s campus where they planned to celebrate what they thought would be a Harris victory.

As television networks began calling several key states for Mr. Trump and showed him leading in others, partygoers’ enthusiasm soon waned.

The event began with students and Harris supporters dancing and listening to Howard’s gospel choir as they sang, “Lift Every Voice and Sing,” which has been dubbed by some as the “Black National Anthem.”

By 11 p.m. the mood darkened considerably and the dancing had stopped. Attendees watched in near silence at the CNN telecast broadcast on a large TV screen next to the stage.

Once North Carolina was called for Mr. Trump, the CNN broadcast was briefly shut off and instead replaced with images of the crowd, some of whom stood agape.