A commitment to deliver (a service, funding, an item) that is subsequently set aside. The broken promise is then explained with the glib expression "oh, but that promise was non-core".Now generalised to non-political situations, too.Origin: Australian federal elections at the turn of the 20th/21st centuries. The conservative party (known as the Liberal/National coalition) made a number of election promises which were broken soon after the election. The prime minister, John Howard , attempted to explain this behaviour by claiming that some promises are "core" and some are "non-core" and thus, don't count.