Amid a steep ratings slide at the "Buffy the Vampire Slayer" network, Les Moonves, the CBS boss who runs UPN, has started talking to the Fox Television Station Group, in hopes of locking in a multiyear affiliation agreement, sources said.

The current deal expires at the end of the next TV season. But Moonves wants a head start because he needs assurances from Fox before investing heavily in a new slate of shows for the stumbling network, sources said.

Fox has tremendous leverage because its UPN affiliates account for about 20% of the network and include UPN’s top three markets, including New York’s Channel 9.

"If the deal is terminated, there will be no UPN," a source said. Fox and Viacom execs declined to comment.

Fox can argue that its stations would be better off without UPN, whose ratings among 18-to-34-year-olds - the group targeted by the network - are down 15% this year.

"Their two franchise shows, "Buffy" and "Star Trek" are down," said Brad Adgate, director of research for Horizon Media. "None of the new shows have clicked."

One option for Fox is to replace UPN with movies and other shows from the vast Fox Entertainment empire, though some said the Fox stations would be sunk without UPN.

In the last round of tough-deal talks, UPN managed to renew its deal with the Fox stations - but only after agreeing to pay a premium price for the rights to "Buffy," a series owned by Fox.

Sources said Fox execs are hopeful that Moonves and his UPN team will present plans for fixing the network, which is about to unveil some new midseason shows. An exec close to the talks cautioned, UPN "needs to be young and unique."

BIZ NEWS RACE

Ratings for financial TV news are down, but PBS’ war horse, "Nightly Business Report" has managed to maintain its viewers.

The 24-year-old show with anchors Paul Kangas and Susie Gharib was watched by 710,000 households in the week of Nov. 4 - equal to its audience last February - according to the most recent figures from Nielsen.

That means "Nightly Business Report" is beating Fox News’ "Your World with Neil Cavuto and CNN’s "Lou Dobbs Moneyline." The PBS biz show is carried in more households than its cable rivals.

"It’s confirmation of a longstanding trend," said Stuart Zuckerman, the program’s vice president, sales and marketing.

LEVIN’S MONEY WOES

Ousted AOL Time Warner boss Gerald Levin refused to be interviewed on the air for "The Big Heist" a one-hour documentary marking the third anniversary of the botched AOL Time Warner deal airing tonight at 9 on CNBC.

But the fallen media mogul’s failed vision for the mega merger and his personal financial woes are among the most important revelations in the program from CNBC anchor David Faber. Levin has been forced to sell stock and put real estate holdings on the block to pay back his loans.

"The depth of Jerry Levin’s financial problems and the willingness of his friends to talk about it are astounding," Faber told the Daily News. "A lot people don’t realize that he never sold a share of AOL Time Warner willingly."