mediar cambio rotundo

Question

I'm having trouble making sense of the following sentence:

Son sus políticas las que, de no mediar un cambio rotundo, lo terminarán ahorcando.

Here is my attempt,

His policies, ..., will end up hanging him.

I don't get "de no mediar un cambio rotundo." I suppose it is an idiomatic expression.

Answer 1

mediar un cambio rotundo: to invoke/make/ make happen a complete change