I think you've got me mistaken for someone else. I just asked if congress has the authority to order the US Marshals to enforce their subpoena.
Oops, sorry. I'm new to this format. *blush*
From what I understand, the USAG can order the Marshals in, but congress may not.
RFK used his power to send Marshals down south to ensure that black students were allowed access to recently desegregated schools in Mississippi, for example. Mississippi had chosen not to uphold federal law, so Marshals were sent in to enforce it.