Will Wilkinson pinpoints a political weakness:
As governor, Mr Johnson showed that a non-ideological, pragmatic libertarianism can work as a governing philosophy. But neither full-blooded libertarians nor allegedly liberty-loving tea-party enthusiasts really care much about governing. Libertarians, accustomed to dwelling on the margins of American politics, participate in elections without hope of electoral success, if they participate at all. For them, presidential campaigns offer at best an occasion to preach the libertarian gospel to the wary public, and the more table-pounding the better.
Alex Massie agrees:
Johnson's style – relaxed, calm, patient – is ill-suited to the times. His principles and beliefs challenge conservatives and liberals alike while offering nothing to the nationalist rassentiment that pervades the Republican party these days. Ron Paul's movement is, fundamentally, based on emotion; Johnson makes the mistake of trying to appeal to reason. That won't work this year.
The Dish 