He has little time and even fewer resources to change that before the Sept. 12 primary. The Albanese campaign has no dedicated office or full-time staff apart from a pair of consultants, and little money in the bank after it furiously raised and spent the required $175,000 to qualify for last week’s debate.

Resources are so slim, in fact, that Mr. Albanese cannot take out a television commercial to introduce himself, or attack the mayor.

Since the debate, some donations have come in, he said, but nothing approaching the $5 million that Mr. de Blasio has in his campaign coffers. Instead, Mr. Albanese has crisscrossed the city holding modest campaign events, recording videos to post on the internet and tapping a network of people whom he met long ago.

“I remember him from back when very few people were coming out to the blocks,” said Richard Green, who founded the Crown Heights Youth Collective, a community group, in the 1980s and was showing Mr. Albanese around the neighborhood a day after the debate.

A lot of Mr. Albanese’s campaigning is like that, peppered with talk of the past.

“Are you Sal?” a kindergarten teacher, Judy Coppola, asked as he walked in Bay Ridge. Mr. Albanese, who worked as a teacher in city schools before running for the Council, stopped to talk.

“I always said, ‘What happened to him?’” Ms. Coppola said after he walked on.

During his time in the City Council, Mr. Albanese got his law degree and was known as a reformer and political maverick, a liberal from a conservative district who wrested the seat from a Republican and held it for 15 years. He voted against the budgets negotiated by the Council speaker, and was rewarded, he said, with a cubbyhole office for his entire tenure.