John McCain should have known better than to cancel his appearance on the Late Show with David Letterman at the last minute, said Tim Harper in the Toronto Star. Since then, Letterman has been skewering McCain. “McCain has rebounded from a number of body blows in his bid for the U.S. presidency—but can he survive the Letterman Effect?”

It might not be easy, said Joe Garofoli in the San Francisco Chronicle online. Shows like Letterman’s “are just as important in establishing a cultural buzz as Meet the Press.” When the comedians start to “turn on you, so does the mass culture, and so do the casual voters.”

Not everyone will be on Letterman's side, said Gary Susman in Entertainment Weekly online. You could argue that Letterman “was churlish for spending some nine minutes of the show mocking McCain's flimsy excuse, or for booking outspoken McCain critic Keith Olbermann as a substitute guest.”

Whatever the case may be, said Sarah Lai Stirland in Wired.com, the footage of Letterman making fun of McCain the night he cancelled has been viewed 1.4 million times on YouTube so far—making it “the most viewed political video of the week.”