NEW YORK, SEPT. 7 -- The New York Post's unions put on a brave face today and said they were determined to keep the tabloid in business, as the clock ticked toward a deadline for far-reaching financial concessions.

"They need the relief or they will go out of business," said Allied Trades Printing Council President George McDonald. "I firmly believe that we have a crisis here."

"We're all concerned and we're going to do everything possible to stay in business," he said.

Citing a flow of red ink that has cost him $80 million in his two years of ownership, owner Peter Kalikow this week threatened to shut down the 189-year-old newspaper by Sept. 15 if he did not achieve up to $25 million in savings.

Two of Kalikow's top executives responded to a request for a brief meeting with leaders of the council, the umbrella group representing the 10 newspaper unions, and both left the meeting before the news conference smiling and trading jokes with some union officials.

Asked how efforts were going to beat the Sept. 15 deadline, one of them, the Post's general manager, Richard Nasti, answered, "Well. Things are good."

The Post agreed to open its books to the unions, and McDonald said KPMG Peat Marwick accountants would pore over the accounts and report back to the unions by early next week.

He said round-the-clock negotiations with Post representatives would begin Monday or Tuesday, although no hotel site had been secured yet.

Job security and other contract rules would be "sacrosanct," and each union will negotiate separately over staffing and salary issues, said Theodore Kheel, a longtime newspaper contract mediator advising the union.

"Unless all of them agree, then the Post will go down the drain," he said.

Nonetheless, the Newspaper Guild, the newspaper's largest union, representing 337 editorial and advertising workers, voted at a meeting Thursday to reject Kalikow's first proposal for cuts that the union said totaled 46 percent in salaries and benefits.

Michael Alvino, president of the drivers union, said his 263 members had not voted on the proposed givebacks yet, but had been asked to accept staffing and overtime cuts worth about 54 percent in costs.

Union officials raised concerns about the impact of contract concessions at the Post on the unions at the city's other three major newspapers, saying they would not cave in to unreasonable demands just to reach an agreement.

"If we happen to fail {to reach agreement on the proposed concessions}, we're not going to blame each other," said McDonald, who repeatedly contrasted the "honest" efforts by the Post with what he called a "cynical" spirit by the management of the Daily News, owned by Tribune Co., which has taken an aggressive bargaining stance toward its unions this year.

McDonald said he was optimistic, but acknowledged that "everybody is still in shock."