A new game-changer?

Nate Silver senses an impending electoral stunt from McCain. All the signs are there: an Drudge-reported uptick in the national polls. A new come-out-swinging tone ("I'll whip him in the you-know-what"). A test-the-water piece from William Kristol in the Times telling him to "fire" his entire campaign. A general feeling of ticklishness in the air. A flocking of the animals to the westernmost quadrant of the field....