From The Academy
Does the Media Reaction to a Presidential Debate Matter?
Yes, according to the University of Chicago's John Sides, who discusses the broader importance (or lack thereof) of debates in an article for the Washington Monthly. One example was particularly striking.
[President Gerald] Ford’s erroneous assertion about eastern Europe in the second debate of 1976 is considered one of the biggest debate gaffes of all time. On the night of the debate, however, none of the debate viewers interviewed in one poll named the gaffe when asked about the ”main things” each candidate had done well or poorly. Only for viewers interviewed the next day did this gaffe become more salient—evidence that the public needed the news media to point out that Ford had made a mistake.
More importantly, Ford’s gaffe did little to affect the main trend in the fall campaign, which was a declining lead for Carter. According to Gallup’s polling, Carter had a 15-point lead before the first debate but only a 5-point lead after the second one. As Erikson and Wlezien put it, “Carter’s downward slide during the fall campaign seems to belie that this debate gaffe did much lasting harm.”