Mayor Michael Bloomberg's administration has spent months lobbying council leaders and trying to reach land deals with the area's largest owners to win support for the development, which, at 62 acres, is three times the size of the Atlantic Yards project in Brooklyn, where the New Jersey Nets want to build an arena.
The $3 billion plan would create 5,500 apartments, a hotel and convention center, stores and office space in an area dominated by garages and salvage yards without sewers.
Bloomberg called the neighborhood "perhaps the most heavily polluted area in the city - maybe even the entire region. And we've long believed that it's also one with the most promise."
A majority of council members signed a letter months ago saying they would not support the project without major changes.
Monserrate on Wednesday said he changed his mind because of the city's commitment to affordable apartments and "a commitment that the city will continue to engage in negotiations with property owners."
The plan would give the city the right to resort to eminent domain to take over the land of owners who didn't want to sell. The city on Wednesday had reached deals with owners of one-third of the space, were negotiating with a contractor that is the largest owner in the area and has promised relocation and job training to most of the businesses.
But several business owners said they had no plans to sell, and they said the owners who did were being unfairly pressured.
Jake Bono, who owns a sawdust supply company, said the city was paying above-market prices for land in an economic downturn.
"The city has no money," Bono said, "but Bloomberg ... still has money to play Monopoly with his friends at Willets Point."
