How does the US Senate compel compliance with their subpeonas?

Question

If the Sentate subpeonas a White House official who refuses to testify, is there an instrument similar to the bench warrant? That is, can they be held in contempt and if so, what penalties or means of enforcement does the congress have? Who are the agents of enforcement?

Answer 1

Yes, Contempt of Congress. 18 USC 1001.

Sadly, the Justice Department is charged with enforcement.