Jane Brophy and the Lib Dems protested against plans to decimate Greater Manchester's greenbelt on Saturday.
The rally in Albert Square was attended by protestors from across Greater Manchester.
"Labour and Conservative politicians are trying to force through this plan. There is another way. As Mayor I will scrap the Greater Manchester Spatial Framework and take a bottom-up approach to meeting our housing needs. We need local communities involved right from the start," said Jane.