Bronx lawmakers threatened to mount an all-out war Thursday if Mayor de Blasio tries to block the expansion of a high-performing all-girls charter school in their borough.

“The mayor of the city of New York has to understand that the state Assembly and the Senate have the power to eliminate the charter of the city and make another city,” Assemblywoman Carmen Arroyo said at a rally outside the Girls Prep Bronx Charter School.

“We have the power. Therefore, he has to work for us,” she added.

Girls Prep, with 372 students in K-5, shares space with MS 302. It is looking to add grades 6-8 at nearby MS 301.