Beck seems not in sufficient control of the centrists in his party (for a reason also see Turambar), but note that he is no leftie put a power politician himself (he used to govern withe the (neo)liberal Free Democrats in Rhineland-Palatinate state until he wan absolute majority). But those writing his obituary seem to come from the right-wing and right-leaning media, people with an agenda; and they are over-emphasizing voices from one wing of the SPD.

That said, I never took the idea of a chancellor candidate Beck seriously. He seems to me more a kingmaker than king. But sorry I have no evidence to quote, just feelings, and I don't live in Germany...

_{*Lunatic*, n.
One whose delusions are out of fashion.}