Leveraging FT Offer to another location

I recently signed a full-time offer with a MM firm (RJ, Stephens, STRH, etc) for a coverage group in a city in the South. However, I just found out that this same firm is re-opening FT positions in NY because a previous intern declined his return offer. My ultimate goal is to work in NY, so would it be feasible to try and negotiate with HR to place me in NY, or is it too late because I already signed my offer for a spot in the South?

Thanks all!