Metro

Dave, rival vow all-out war

They’re two stubborn, furious men playing a high-stakes game of chicken.

David Letterman has flung down the gauntlet, vowing yesterday to take down the CBS producer whose alleged $2 million extortion scheme exposed Letterman’s philandering to his wife and fans.

And he’ll press his case even if it means testifying at what’s sure to be an embarrassing, high-publicity trial.

But the alleged extortionist, Emmy-winning “48 Hours” producer Robert “Joe” Halderman, isn’t backing down, either. He, too, is threatening to fight his case all the way to a jury verdict, even though a conviction could get him up to 15 years in prison.

And he’ll do his fighting with an intriguing argument first revealed yesterday — that his demand for $2 million wasn’t a shakedown, but a legitimate business proposal.

Halderman was merely offering Letterman first dibs on a screenplay and book based on the life of an intern-loving TV host whose world was about to collapse, said his lawyer, Gerald Shargel.

Shargel argues that his client never even met with or spoke to Letterman directly — and that if Letterman had declined through his lawyer to buy the one-page “treatment,” Halderman would have simply sold it elsewhere.

Shargel also hinted that the mud would continue to fly in a case that has already exposed Letterman as a serial seducer of interns over two decades.

“You’ll learn more about that,” a smiling Shargel taunted when asked whether Letterman lied about when his affair with former “Late Show” intern Stephanie Birkitt ended. The lawyer declined to elaborate.

Birkitt reportedly was still seeing Letterman even as she shared a bed with Halderman in his modest Norwalk, Conn., home.

Halderman threatened to expose Letterman after catching the comic and Birkitt in a passionate embrace in August, sources have said — less than half a year after Letterman married his girlfriend of two decades, Regina Lasko, the mother of their 5-year-old son.

“Mr. Letterman is fully prepared to see this case through to the end, including testifying at trial,” his lawyer, Daniel Horwitz, told reporters yesterday.

Horwitz scoffed that if the “treatment” had been legit, Halderman would not have been “waiting in the shadows” outside Letterman’s TriBeCa apartment at 6 a.m. to hand it to the talk-show host’s limo driver — and would not have demanded a response by 8 a.m.

“It’s classic blackmail,” Horwitz said.

laura.italiano@nypost.com