An agreement appears close between New York Mayor Bill de Blasio's administration and the United Federation of Teachers for a new contract, a union source said last night.

The teachers have been without a contract since 2009 and have been demanding billions of dollars in raises and back pay.

The final language for a new labor agreement was still being worked out, the source said.

"We'll have a better idea of the status in the morning," the source said.

De Blasio's scheduled major announcement Thursday of his plans to expand affordable housing was postponed because of labor discussions, administration sources said. The mayor's press office had no comment on the status of the UFT negotiations.

The UFT represents 75,000 teachers and tens of thousands of other school employees, accounting for one of the biggest chunks of the city's 300,000- strong workforce, most of which is unionized.

A UFT settlement could set the tone for the rest of the open labor contracts -- firefighters, police, sanitation workers and more.

The teachers union has been clamoring for retroactive raises that former Mayor Michael Bloomberg said the city could not afford without going into a budgetary sinkhole, an assertion that labor union economists dispute.

The de Blasio administration has been tight-lipped on how much of a raise if any to give teachers, but has sought concessions on health insurance contributions.

If the deal is completed and ratified, it would be de Blasio's first major contract settlement. Every one of the 150-plus municipal contracts lapsed under Bloomberg, a situation that de Blasio complained was "unprecedented."

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The Bloomberg administration countered that the unions bet a Democrat would succeed him and thought they could get a better deal with the successor.

At a UFT conference on Saturday, de Blasio spoke to rousing applause and standing ovations.

"Can't think of anyplace else I'd rather be, to tell you the truth," he told the union members.