There is a theory (known as market monetarism) that central banks can control nominal growth. Predicated on the Quantity Theory of Money, it asserts that the central bank, by controlling M (with V assumed to be within a bounded range) can control nominal GDP*.
Politicians can tune up the engine and improve efficiency (the supply side), but they do not control the throttle (aggregate demand); only the central bank does.
If one steps back and looks at the developed countries today, what is the #1 problem that they all have in common? Answer: low nominal growth, resulting in inadequate employment and tax revenue.
Global nominal growth levels have been falling for thirty years. During the non-recessionary years of the Clinton-Bush era, the US enjoyed nominal growth of >6%%. Today, post-crash, the US remains stuck in second gear at 4%, which had been considered recessionary.