Remember "pick a number," a method for picking who bats first or some other either/or decision? To pick a winner between two people, a third person says "I'm thinking of a number between 1 and 100." He then asks one of the two to take a guess and then the other, with the closest guess winning. At some point in your childhood you perhaps were impressed when the guessing went like this. A: 19. B: 20. B has realized that by picking 20 that he now has an 80% chance of winning, since any number between 20 and 100 will be closer to 20 than 19. I wish I could say that I figured this out myself and used it before seeing anyone else do it, but at least I recognized it when it happened. It seemed pretty brilliant at the time, but I realize now that its success depended on certain assumptions. The first assumption is that all numbers between 1 and 100 are equally likely. If the person picking the number was a three year old who could only count to 30 (he's heard rumors of 100, but doesn't know anything about it), 18 is probably a better guess for B than 20. The second assumption is that there are only two contestants. If a third person C is involved, 60 is probably a better guess than 20.
So, if haven't already seen where this metaphor is leading, allow me to (metaphorically) beat you over the head with it. The person picking the number represents the range of political positions in the American public--1 is far right, 100 is far left. A is the Republicans, B is the Democrats, and C is the Greens or other third parties. Both A and B have realized that their chances are improved by not allowing C to pick a number, so they do everything they can (which is a lot) to prevent that from happening. B, the Democrats, think they are pretty smart, picking 20 to the Republicans 19, figuring everyone to the left of 20 will vote Democratic. The problem is that by debating between 19 and 20 and excluding anyone who would pick higher numbers, the voting public has become like the kid who can only count to 30. Many are deceived that the Democrats are actually liberal, while others are up in the 70's and 80's, from which no real difference between A and B is discernable, so they don't vote at all. The Democrats, considering themselves brilliant by picking 20, have actually put themselves at a disadvantage by helping the Republicans reduce it to a game of 1 to 30. And any Democrat who starts to figure this out gets killed in a plane crash.