But he has yet to win vital support for his plans from Mayor Bloomberg.

The mayor said again yesterday that he's "not a believer" in the need for 10 million square feet of office space and also fears the prolonged construction of four more office towers will scare off prospective tenants.

In an interview on WABC-AM radio, he said, "I am very strong on getting a lot of these things going simultaneously rather than consecutively, because it is harder to rent space when people say, 'This is going to be a building site for the next 15 years.'"

Bloomberg has proposed making housing a big part of the mix at the site.

In a further challenge to Silverstein, Bloomberg added, "Maybe one developer can do it all, and maybe different developers can do [it] simultaneously."

Silverstein, who is finishing up the 52-story 7 World Trade Center building, wants to put the Liberty Bonds toward four of his five other proposed office towers.

Bloomberg wants the two towers at the southeast corner, "which sort of connect the ... site to the rest of the downtown," to get underway "at the same time as the others."

Silverstein, who is due to start the 1,776-foot Freedom Tower this spring, says in his bond application that he'd spend the proceeds on construction at the site through 2015.

Next Thursday's hearing is before the board of the New York City Industrial Development Agency. The panel will later vote on the bond package, if it's first approved by the city and state.

In an analysis released late yesterday, the agency said the four towers will cost a total of about $7.5 billion and hold 35,200 officer workers.

Bettina Damiani, project director of Good Jobs New York, said Silverstein's stated assumption that he'll lease 40% of each tower in the first year is "overly optimistic." She questioned whether the bonds are a "wise investment for taxpayers."

Early this week, Silverstein said, "There's little doubt in my mind that we will work this through and get it [bond approval] done."