Amid growing public dissatisfaction with Mayor Eric Adams’s job performance, the New York City Council speaker, Adrienne Adams, was about to make a power play.

Ms. Adams was preparing to introduce legislation on Thursday that would require the mayor to obtain Council approval on 21 commissioner-level appointments, according to a draft of the bill that the speaker’s office shared with The New York Times.

The move would significantly curtail the mayor’s authority by adding a level of Council oversight.

It would require a citywide voter referendum, because it proposes to curb the power of the mayor. The only way Mr. Adams could stop such a referendum is if he were to create a Charter Revision Commission that would have the power to decide what, if any, ballot initiatives might be placed before voters.

Sure enough, a few hours after The Times sought comment on Tuesday from the mayor’s office, it put out a news release announcing the formation of a Charter Revision Commission, which would consider changes in the governing document that is equivalent to a city constitution. Only one member was named; other names, the release said, would be forthcoming.

The maneuvering underscored how the relationship between the Council and the mayor’s office has reached a new low during a time of acute vulnerability for the mayor. Mr. Adams is up for re-election next year while facing a federal criminal investigation and historically low poll numbers. He already faces two likely challengers in the Democratic primary.

The proposal, which a spokesman for the speaker said she still plans to introduce on Thursday, also underscores concerns about the mayor’s tendency to put a priority on personal loyalty when filling important positions.