In a couple of pages in “Birth of Biopolitics,” Foucault demolishes the idea of liberal socialism (of socialism as the means by which liberalism’s promises are truly and finally fulfilled).
Liberalism has a governmental rationality (whether you like it or not). Socialism doesn’t

Socialism, he notes, certainly has a historical rationality. It also has an economic rationality.
But it lacks an independent governmental rationality or “governmentality.”
Socialism, he says, derives its governmental rationality from other systems. Typically liberalism.

Hence why — this is now me, extending Foucault — liberalism always takes over the formula and ultimately prevents the fulfillment of socialism’s own historical and economic rationalities.

We might say — again, this is me, playing with F’s ideas — that socialism lacks a governmentality because, in its main Western strands, socialism lacked an independent philosophical anthropology. It assumed into itself liberal anthropology.