President Obama has unveiled a new plan to use executive authority to cut power plant emissions of CO2 by 30 percent, and as Jon Terbush noted, this is a big deal in Kentucky. In fact, it's such a big deal that Senate Minority Leader Mitch McConnell's Democratic opponent, Alison Lundergan Grimes, is running ads in newspapers criticizing President Obama for the move:

There are basically two ways to handle something like this. You can stick with the president, or you can divorce yourself from him on this issue — criticizing him from the right, as Grimes is doing. But here's the important point: She has the latitude to make this move.

And why does Grimes have the latitude to criticize a sitting president of the same party? Democratic voters and liberal outside groups (and, no doubt, Harry Reid and President Obama) are pragmatic enough to know it's all theater. They are smart enough to know that she will probably vote the liberal line once she's in office, and the primary objective is to do whatever it takes to get her there. If criticizing Obama is what it takes to win in Kentucky, well, that's just the cost of doing business.