# Can the Fock-Schwinger (radial) gauge condition be written as momentum space divergence?

The Lorenz Gauge can be written (in QED) as $$\partial^{\mu}A_{\mu} = 0$$ or equivalently as $$p^{\mu}A_{\mu} = 0$$. The Fock-Schwinger gauge is similar: $$x^{\mu}A_{\mu} = 0$$.

Can it be written equivalently as $$\frac{\partial}{\partial p^{\mu}}A^{\mu} = 0$$, or is this naive?