NEW YORK — It's Letterman vs. Leno, redux.
With Conan O'Brien's exit official, CBS's David Letterman and Jay Leno are set to renew head-to-head competition at 11:35 p.m. EST on March 1 when Leno returns to "The Tonight Show" on NBC.
NBC and O'Brien agreed to a $45 million deal early Thursday morning, ending the late-night battle between O'Brien and Leno that had brewed for two weeks after the network announced it planned to cancel Leno's experiment in prime time.
The Leno-Letterman rematch comes at a time when their feud is in full bloom. Throughout the fallout with O'Brien, Letterman has regularly mocked Leno on "Late Show." He has called him "Big Jaw," done a high-pitched impression and said "vintage Jay" had been revealed.
Even though Letterman has said he "doesn't have a dog in this fight," his sympathies have clearly been with O'Brien. Letterman went through a similar situation when Leno stepped over him to succeed Johnny Carson on "Tonight."
Their squabble was memorably portrayed in the 1996 TV film "The Late Shift." In the past two weeks, Letterman has repeatedly referred to the details of that fallout — such as Leno eavesdropping on NBC executives by hiding in a closet.
After Leno landed "Tonight" in 1992, Letterman left NBC and set up his rival "Late Show" in 1993. Since then, the two have competed for 16 years, with Leno usually winning easily in the ratings.
Before the current mess, Letterman had seemed to have moved beyond any dislike of Leno. In a 2008 interview with Rolling Stone, he questioned NBC moving Leno out of late-night and said he "has greater appeal for more people than I do."
But clearly old wounds haven't healed, as Letterman's glee has shown.
"I'm telling jokes and making fun of Jay Leno over and over and over, relentlessly, mercilessly simply for one reason," Letterman said on Monday's show before pausing and smiling hugely: "I'm really enjoying it."
Leno fights back
On the prime-time "The Jay Leno Show," Leno has punched back. In particular, he's using as ammunition Letterman's admission last year of having had affairs with members of his staff.
More Entertainment stories
Autistic ballerina dances her way into hearts
In a popular YouTube video, the beaming little ballerina dances an entire four-minute routine seemingly perfectly, matchin...
- Every on-screen drink in 'Mad Men' in 5 minutes
- See the 'Dancing' stars' most memorable moves
- Emmy's biggest snubs? Cranston, Hamm, more
- 'Toy Story' toys burn up in prank on mom
- Autistic ballerina dances her way into hearts
"Letterman has been hammering me every night," Leno said on Wednesday's show. "You know the best way to get Letterman to ignore you? Marry him. He will not bother you. He won't look you in the eye."
Slideshow: Cartoons: Fight for late night Last week, Leno said Letterman's attacks surprised him because "usually he's just taking shots at the interns."
Their sniping has been one of the most captivating sideshows to the O'Brien-NBC debacle.
How it will play out once Letterman and Leno are again front and center — without O'Brien in the middle — will be another issue.
The dynamic has long been that Leno triumphs in ratings thanks partly to his "Mr. Nice Guy" image, while Letterman wins with critics.
But Leno's image may have been battered in retaking "Tonight" — Letterman has been far from alone in his criticism. Among the many comics to take the side of "Team Conan," ABC's Jimmy Kimmel was perhaps the most ruthless, doing an entire episode of "Jimmy Kimmel Live!" in a scathing Leno impression.
And Letterman's ratings have been up recently. The "Late Show" averages about 4.2 million viewers, according to Nielsen figures. That, however, is still less than the 5.3 million nightly viewers "The Jay Leno Show" has averaged at 10 p.m. since its fall debut — about the same number he got as host of "Tonight."
Who will come out on top?
Doug Spero, an associate professor of mass communication at Meredith College in North Carolina and a former TV news director and NBC employee, said the back-and-forth between Leno and Letterman works as both "self-promotion and cross-promotion."
Video: Leno to return as 'Tonight' host "Letterman has picked up strength," said Spero. "After a certain amount of time, Leno will come back and win slightly. But I don't think he'll ever be as strong as he was."
Jeff Gaspin, chairman of NBC Universal Television Entertainment, said NBC expects Leno to "be competitive right away." Gaspin said Leno's image isn't hurt much because the situation has been "inside-Hollywood" and that Middle America doesn't "have any clue what's going on behind the scenes."
"We believe Leno will be the late-night leader again," said Gaspin.
Marc Berman, who writes "The Programming Insider" for Media Week Online, questioned Gaspin's prediction.
"The dynamic has changed because now Leno is going in as the underdog," he said. "Leno looks like a laughing stock, so that gives Letterman the upper-hand. I don't assume Leno is going to bring back every viewer he ever had."
As for a Letterman-Leno smack down, Spero said, it reminds him of "the good old days of real competition."
"I don't know if it's healthy or not for the industry," he said, "but at the very least it's fun."
Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.