These are two excerpts from an interesting piece on the invention of political consulting (from The New Yorker):

THE LIE FACTORY. How politics became a business.  By Jill Lepore

Never underestimate the opposition. The first thing Whitaker and Baxter always did, when they took on a campaign, was to “hibernate” for a week, to write a Plan of Campaign. Then they wrote an Opposition Plan of Campaign, to anticipate the moves made against them. Every campaign needs a theme. Keep it simple. Rhyming’s good. (“For Jimmy and me, vote ‘yes’ on 3.”) Never explain anything. “The more you have to explain,” Whitaker said, “the more difficult it is to win support.” Say the same thing over and over again. “We assume we have to get a voter’s attention seven times to make a sale,” Whitaker said. Subtlety is your enemy. “Words that lean on the mind are no good,” according to Baxter. “They must dent it.” Simplify, simplify, simplify. “A wall goes up,” Whitaker warned, “when you try to make Mr. and Mrs. Average American Citizen work or think.”

(…)

“Voters are basically lazy, basically uninterested in making an effort to understand what we’re talking about,” the Nixon adviser William Gavin wrote in a memo. “Reason requires a higher degree of discipline, of concentration; impression is easier,” he wrote in another memo. “Reason pushes the viewer back, it assaults him, it demands that he agree or disagree; impression can envelop him, invite him in, without making an intellectual demand. . . . When we argue with him we demand that he make the effort of replying. We seek to engage his intellect, and for most people this is the most difficult work of all. The emotions are more easily roused, closer to the surface, more malleable.”