Assemblyman Zohran Mamdani, the Democratic nominee for mayor of New York City, said on Sunday that he was visiting Uganda, where he was born, in a break from campaigning for the general election in November.

In a video posted on X and Bluesky, Mr. Mamdani said he was making the trip to Africa with his wife, Rama Duwaji, whom he married in February, to celebrate their marriage with family and friends.

He left the city during the traditional summer lull in the weeks after the June primary, while, at the same time, his most formidable opponent, former Gov. Andrew M. Cuomo, was seeking to strengthen his own run on an independent ballot line with appearances across New York in the aftermath of his surprise defeat by Mr. Mamdani.

In a statement, Mayor Eric Adams, a Democrat who is running for re-election as an independent, criticized his opponent for taking a vacation. (Mr. Adams has taken numerous trips abroad before and after becoming mayor, including a weeklong “spiritual journey” to Ghana shortly after his election in 2021.)

“At a time when public safety, housing, and education remain top concerns for working New Yorkers, the mayor is here — managing the responsibilities of running the largest city in America,” Mr. Adams said in a prepared statement. “This election is about who’s prepared to lead, not who can rack up the most passport stamps or press headlines. Eric Adams is working. Others are sightseeing.”

A spokesman for Mr. Cuomo did not immediately respond to a request for comment.

Mr. Mamdani’s spokesman, Jeffrey Lerner, said in a statement that the candidate would return to New York before the end of the month “and looks forward to resuming public events and continuing his campaign to make the most expensive city in America affordable.”