"I've got nothing against high-end development," Quinn said on Thursday. "In fact, this Council approved much of it. But no one could have predicted this. Thousands of those homes never sold, left like tarnished trophies of the building boom. These vacant apartments now represent our best asset in the fight for affordable housing."

Where developers have units they cannot sell, said Quinn, "the city will negotiate the lowest possible price, and make these homes affordable for middle-class families to rent or buy. Using existing funds, we'll add thousands of new affordable homes." She adds that the program would add the affordable stock via units that are "already out there, just waiting for someone to call them home."

A spokesman for Quinn tells GlobeSt.com that participation in the program would be strictly voluntary on the part of developers. The city would also provide a "funding supplement" to help cover developers' expenses through the program, although the spokesman adds, "it wouldn't be to provide a windfall profit."