After years of nail-biting escapes from financial oblivion, the New York Post may finally have run out of miracles.

Publisher Peter Kalikow, who rescued the tabloid when former owner Rupert Murdoch wanted to close it in 1988, has threatened to stop publishing Saturday unless the paper's 10 unions agree to sweeping wage cuts and layoffs that would save $17 million. Kalikow said the 189-year-old paper has lost $80 million in the last two years, and sources said his bankers refuse to lend him more money unless he stems the flow of red ink.

Union officials had their auditing firm examine the Post's books yesterday and said later they believe the losses are real and hope to begin round-the-clock negotiations today.

Kalikow, a Manhattan real estate developer, would be required under federal law to pay his 960 employees for 60 days after a shutdown announcement.

The Post's quirky flamboyance and screaming headlines (such as "BEST SEX I EVER HAD" and "READ MY LIPS: I LIED") have earned it a permanent place in most New Yorkers' hearts. But it has consistently come up short in competition with the Daily News, New York Times and New York Newsday, capturing only 7 percent of the market's advertising revenue.

"It's always been dependent on being owned by somebody with very deep pockets who was willing to dip into them," said newspaper analyst John Morton. "Presumably Mr. Kalikow is losing his appetite for that. There just isn't room in New York for that many papers anymore. The Post has been the odd paper out for a long time."

Still, both sides say a shutdown can be averted. "Labor and management both want this paper to survive," said Kalikow spokesman Gary Lewi.

"I feel optimistic about it," said George McDonald, president of the Allied Printing Trades Council, the unions' umbrella group. "If the unions fail, nobody's going to blame anybody. The Post management has been up front with us. They're a different type of management than the people across town at the Daily News, who are trying to kill us."

Union officials have launched a media campaign urging advertisers to boycott the Daily News following a nasty, five-month deadlock in which News management has demanded deep cuts in staffing levels for pressmen and drivers. Although relations with Kalikow are more amicable, the Post is saddled with similarly generous staffing levels critics describe as featherbedding.

"The problem for the unions is that if you give {concessions} to the Post, the Daily News will want it, the Times will want it," Morton said.

News executives are attentive. A Post shutdown "certainly would be a sad thing for the city, but I'm not going to lie and say competing newspapers would be crying in their beer," said Daily News managing editor Matthew Storin. "You don't have to be a rocket scientist to realize that if there was no Post next week, more people would pick up the Daily News."

But even the Post's demise would not necessarily revive the News, which has lost 700,000 in circulation in the last decade. Analysts say the Post is a second paper for most people. Many of those readers "will just disappear," Morton said.

The shutdown threat has decimated morale in the paper's South Street newsroom. "This was like an atomic bomb dropping on a peaceful country," said reporter Bill Hoffmann. "All weekend we were calling each other saying, 'You got anything lined up?' The reporters always think of this as 'our' paper, but it's really just businessmen doing their deals."

Hoffmann said Newspaper Guild-represented reporters and editors were unlikely to accept the 30 percent pay cut proposed by Kalikow. The only alternative, he said, would be drastic editorial cutbacks that would turn the paper "into a shoestring operation with a few crackerjack rewritemen."

Kalikow lost $25 million last year by starting a Sunday edition and folding it after just three months. He also tried to revitalize the paper by replacing editor Jane Amsterdam, whom he had hired a year earlier, with former WRC-TV vice president Jerry Nachman.

The Post also is caught by the recession in newspaper advertising. Advertising lineage in the first half of 1990 dropped 14 percent at the Post, 16.4 percent at the Daily News, 12.1 percent at Newsday and 11 percent at the New York Times.