Slang among
political ops for "I am
looking for dirt on your candidate." May or may not be connected to the classic line from The Godfather: "Clemenza sleeps with the fish." Meaning he's been whacked, per orders. So "Fishing for your Goombas," maybe, started out meaning "
looking for the bodies in your candidate's background." (Classically such bodies would be a live boy or a dead girl).
"Hey, what's this bullshit with a guy with a camera in the
parking lot at four
in the morning?"
"I am fishing for your Goombas, asshole. If your boy can't keep it zipped,
the people got a right to know."