Letterman Gaining on Leno

The rise of CBS in the prime-time ratings wars may be changing the balance of power after the 11 o'clock news. Jerry Seinfeld could also be partly responsible.

David Letterman, the host of the CBS late-night talk show that's been No. 2 in the ratings for much of the past decade, is gaining ground on NBC rival Jay Leno.

Letterman, who left NBC after he was passed over to host The Tonight Show, has been known to grouse that CBS's weak position in prime time has hurt the ratings of his show. NBC's Tonight Show beat the CBS Late Show in November sweeps by the narrowest margin in three years among the lucrative 18-49 demographic, according to preliminary number crunching from CBS. It's been a decade since the gap among 25-54s has been this small.

So now Letterman can't complain about his lead-in from CBS. The network just pulled off its first November sweeps victory since the 1980s.

Letterman's ratings were also helped by another former NBC star --  Jerry Seinfeld, whose sitcom helped NBC consolidate its dominance on Thursday nights. That was one of Letterman's most-watched shows of the month, as was one featuring shock jock Howard Stern.

Late Show debuted on CBS in 1993, quickly moving ahead of The Tonight Show in the ratings battle. But interest in the new show faded fast and Letterman hasn't won a November sweep since 1994.

Final results for the two shows weren't available as of press time because late-night ratings are released about a week after those for prime time.

But with three days left in the period, The Late Show averaged a 1.8 rating/8 share in adults 18-49 and 2.2/9 in adults 25-54. The Tonight Show was still ahead with a 2.1 rating/9 share in adults 18-49 and 2.4 rating/10 share in adults 25-54.