text: After a strong debut week, O'Brien's total audience fell precipitously over the summer months, and the program began losing to Late Show with David Letterman in overall ratings. In contrast, O'Brien's performance in the crucial 18–49 demographic was favorable, and it was found that he had brought down the median age of The Tonight Show audience by a decade compared with his predecessor, indicating that a generational shift was taking effect as O'Brien established himself in an earlier timeslot. Taking this into account, columnist Tom Shales assessed in August 2009 that O'Brien was in a better position than Leno had been when he began his Tonight Show run in 1992; Leno consistently lost to Letterman in the ratings for eighteen months before eventually cementing his number one status.
  The Jay Leno Show debuted in September 2009, three months into O'Brien's Tonight Show tenure, performing to significantly lower ratings than the primetime dramas it had replaced on NBC and trailing the competition. NBC had expected the drop, having calculated that lower ratings would be balanced by a talk show's correspondingly lower expense compared to more popular scripted programming. In the 11:35 period, The Late Show would largely maintain its lead over The Tonight Show in total viewers in early Fall, during which Letterman was receiving tabloid attention due to a blackmail scandal. In addition, The Tonight Show with Conan O'Brien was in the unusual situation of being a talk show following a talk show hosted by its predecessor on the same network, and the booking war that resulted often left The Tonight Show getting second dibs on guests. One publicist reported that the aggression was such that The Jay Leno Show had signaled to potential guests that doing O'Brien's program before Leno's would be punished with secondary placement in the line-up.