Well, first and foremost, anything is possible, however slim in today's market because most developers are not in the business to trade properties where mortgages payments exist while trying to sell. Also, a lot of the developer's capital comes from the buyers before they break ground on the project. Additional monies are collected throughout the project to keep the developer's risk low.
Saying all that, in order to make this work for you, you would need to present your offer to the developer in a favorable way - where his equity position is very much greater than yours, if that makes sense.
Hope this helps.