2 new ideas about why Barack Obama didn't come to Wisconsin to campaign for Tom Barrett.

From Tobin Harshaw:

The first is that Barrett in recent weeks has attacked Walker for becoming a "rock star" in the national conservative movement, and may have felt that bringing in his own party's rock star would have undermined that effort.

The second, and more likely, is that Barrett made his criticisms of Walker's job-creation record -- not collective-bargaining rights -- the focal point of the race. Given Friday's May jobs report that showed national unemployment on the rise and the fewest jobs added in a year, perhaps the "efficacy" of a presidential visit really was called into question.