The City Council is expected to approve a measure Thursday that would expand its power over the mayoralty, changing the nature of how future administrations are staffed at the highest level.

The bill, which is expected to sail through a committee Thursday morning before going up for a vote of the full Council in the afternoon, would require the Council’s consent for the mayor to appoint some 21 key city agency commissioners.

Mayor Eric Adams, whose appointments have come under intense scrutiny, is already pushing hard against the measure. But he’s been overridden twice when he’s gone up against Council Speaker Adrienne Adams and this time promises to be no different. Councilmembers say if they ultimately prevail, it could result in an administration that is more accountable to residents, rather than just the one person occupying the mayor’s office.

“It’s about good government and effective governing,” Speaker Adams told reporters during a City Hall press conference last month, when she introduced the legislation. “We think it’s an important conversation to have. Commissioners serve the city and all New Yorkers, not a single official, just like all of us do.”

In its current form, the proposal applies to only about a quarter of more than 80 agency heads who help run the city. It would apply to future heads of sanitation, parks, transportation, health and emergency management, among others, and would not affect any current commissioners.

Since the bill would alter the functions of government branches, it has to go before a citywide vote as a ballot referendum. In a move that could possibly delay that process, the mayor formed a Charter Revision Commission last month that could come up with its own ballot initiative instead.