Baltimore city school board members haven't done the best job of explaining their decision to lower the minimum passing grade for key subjects such as math and reading from 70 to 60. But campaign politics is really turning the issue on its head. When Mayor Martin O'Malley, who had nothing to do with the decision, defended it, a spokesman for Gov. Robert L. Ehrlich Jr. said that the governor was "stunned and disappointed" that city leaders could lower expectations for students so easily. But does Mr. Ehrlich feel the same way about students in Howard, Montgomery or Baltimore counties, where the grading systems are the same as the one Baltimore has now adopted? Why are they allowed to pass with a 65 but city kids shouldn't be?