No other politician came close in the overall disapprobation of the citizenry. Senator Chuck Schumer, Gov. Andrew M. Cuomo and Senator Kirsten Gillibrand (who, like Mr. de Blasio, is also running for the Democratic presidential nomination) all had net positive ratings in the poll.

For Mr. de Blasio, it is a problem that has dogged him since he first talked about running for president months ago: How can he win over voters in Des Moines and Las Vegas if people at home don’t seem to like him?

For both Mr. de Blasio and Mr. Trump, there are nuances in the numbers.

Mr. de Blasio has earned consistently favorable numbers from black voters during his two terms, while white voters reject him. Yet, while he easily won re-election in 2017, the Siena poll showed that even in New York City he earns an overall unfavorable rating from registered voters, with more than half voicing a negative opinion.

Even within the Democratic Party, registered voters in New York gave Mr. de Blasio a thumbs down — with 45 percent saying they did not like him, compared to 39 percent who said they did.

Mr. de Blasio has said that he is not concerned by poor polling numbers and that the only poll that counts is when voters cast their ballots.