The standard by which Democratic candidates are now ordained.
Republican primaries are magnitudes more competitive these days than Democratic ones. Do you know about this thing called the Tea Party? A primary is literally all that most Republican politicians are afraid of these days; they're certainly not afraid of general elections, because they would otherwise not say half of the crazy stuff that they do. Which leads into what is offered when the first quote is questioned:
Tea Partiers that aren't backed by big money astroturf groups or by their own self funding go nowhere.
Yet up until they are defeated, we tend to see far more support from the Republican primary electorate for these underfunded sorts than we do in Democratic primaries for their equivalents. My original point is that the Democratic electorate is far more self-defeating in this regard. It's why we continue to be dragged to the right along with the Republicans.