The "line of the day" was an invention of the Reagan campaign. As Mark Hertsgaard described it in his brilliant book On Bended Knee: The Press and the Reagan Presidency, the campaign--and the administration, which was a sort of perpetual campaign--decided every day that Reagan was going to talk about only one thing that day. They worked out the theme, sometimes even the words he was going to use on every occasion. (Reagan was a screen actor: he was used to learning his lines.)
What's more, everyone else working for the campaign, and then the administration, had to say the same thing. No one was allowed to muddle the message. As Deputy Chief of Staff Michael Deaver wrote:
The point of having a line of the day was to get, not just the press saying something, but to get 100 or 200 people saying the same thing in venues all over Washington and the country. And if we could control that message and repeat it constantly, it would have a much better chance of becoming reality.Now, what Reagan and Deaver pioneered, George W. Bush and Karl Rove repeated, as farce. W has, in effect, a line of the administration. As Stephen Colbert observed at the National Press Club: "When the president decides something on Monday, he still believes it on Wednesday - no matter what happened Tuesday." After years of Bush, Cheney, and their surrogates repeating lies no one believes any more, it's actually refreshing to see campaign advisors--and candidates!--shoot from the hip. This may be the historical legacy of the last eight years.