A group of charter school advocates, business leaders, and legislators is pushing to abolish a state-imposed cap on the number of charter schools that can operate in Boston and other low-performing school districts, under legislation expected to be filed Friday on Beacon Hill.

The proposal is anticipated three years after the Legislature and Governor Deval Patrick decided to double the number of charter school seats in those districts. That change created the opportunity for about 5,000 additional students in Boston to attend charter schools.