NBC was reportedly scrambling yesterday to secure a replacement for “Late Night With David Letterman” while exex huddled to discuss ways to put the proper “spin” on what could be a bruising session this afternoon with assembled TV critics.Meanwhile, it appears that Dana Carvey, signed to an exclusive deal last summer as a potential hedge against Letterman’s exit, won’t host a late night show to fill the breach, preferring to focus on his “Wayne’s World”-boosted movie career. That leaves the network with the options of moving up “Later With Bob Costas” and expanding it to an hour or finding a new format and/or talent–hopefully soon enough to avoid a skewering by the press and affiliates. NBC executives, said to be looking for ways to soften that response, may suggest that the furor surrounding its late night soap opera was largely a media creation and not due to mishandling on the network’s part. Press perception clearly leans in the latter direction, with one critic asking CBS/Broadcast Group prez Howard Stringer on Tuesday whether NBC had “botched” the Letterman affair. Today’s press conference in Santa Monica with NBC Entertainment chief Warren Littlefield is scheduled for late afternoon, seemingly calculated to make it difficult for many print reporters– particularly those on the East Coast–to provide substantial coverage regarding the loss of Letterman until Saturday editions. Sources say NBC also considered loading up programming announcements to diffuse coverage of today’s press event–to be attended by about 75 out-of-town critics as well as local reporters– so it isn’t just a Letterman slugfest. Officials wouldn’t confirm reports regarding Letterman yesterday and discouraged both the Leno and Letterman camps from discussing the matter. Still, there were indications the issue has been resolved, including a scheduled Leno appearance on Monday’s “Today” program. Costas also turned up on Tuesday’s “Late Night” touting an upcoming “Later” prime time spec. Published reports say CBS scuttled any chance of NBC re-signing Letterman with a clause involving a massive penalty payment if his show isn’t scheduled at 11:30 p.m., making it virtually impossible for NBC to match the contract terms. Letterman, 45, will celebrate his 11th anniversary on “Late Night” Feb. 1. Though the controversy has focused on his failure to get “The Tonight Show” when Johnny Carson retired, the comic also was miffed to learn of Jay Leno’s ascent to the chair secondhand and by the sale of “Late Night” reruns to cable web A&E. According to sources, one significant player in the Letterman drama has been Peter Lassally, the former “Tonight Show” exec producer who joined “Late Night” after Carson ended his run. Letterman’s producers, Robert Morton and Lassally, would come with the host to CBS. Another variable in the late night equation is “The Arsenio Hall Show,” distributed by Paramount Domestic TV and cleared on roughly 40 CBS affiliates, including eight of the top 25 markets. At a press conference yesterday, Paramount TV Group chairman Kerry McCluggage said the studio expects stations carrying “Arsenio” to honor their contracts but noted that Par may consider shopping the show to other stations in those markets if necessary. Affils that downgrade the talker to make room for Letterman face stiff penalties. Hall recently re-upped for two years, making the stations liable for the difference in ratings over the remainder of their contracts. In addition, many stations carry Paramount programs in other dayparts, such as access strips “Entertainment Tonight” and “Hard Copy,” and would be reluctant to hurt their relationships with the distributor. Even with the financial hurdles that Par could throw in the way, “Arsenio” has seen declining ratings in recent sweeps–a factor CBS affils must weigh as they decide whether to make the switch. Earlier this week CBS exex declined comment on whether the web would defray station costs to break contracts in order to air a Letterman show “live” at 11: 30 p.m., but Stringer predicted the show would be near 100% live clearances and that the web won’t “roll over and play dead” on the clearance issue. CBS’ current “Crimetime After Primetime” action shows reach 87% of the U.S., on 167 of the web’s 200-plus stations, and are delayed in roughly half those markets. ABC’s late night magazine “Nightline” airs “live” in less than 65% of the country. Despite the threat posed by Letterman, McCluggage said Paramount “believes in the long-term future of ‘Arsenio.’ “ NBC gave Letterman permission to talk to outside parties in exchange for extending his contract (which was to expire in April) through June, meaning a CBS show could start at the earliest in July.