Mayor Bill de Blasio’s presidential dreams had better not make him too neglectful of his day job — or he could lose it, under a never-before-used clause in the city charter.

The poison pill buried in the document’s dense legalese is the “committee on mayoral inability,” a five-member body with the power to declare the mayor “temporarily unable to discharge the powers and duties” of the office.

Comptroller Scott Stringer — who has publicly worried about the mayor’s distraction — is a member, along with City Council Speaker Corey Johnson and Bronx Borough President Ruben Diaz Jr., the longest-serving of the city’s five beeps.

The committee would also include two mayoral appointees, Corporation Counsel Zachary Carter and a deputy mayor to be named later, by de Blasio himself.