hammer away at (someone)
To intensely or vigorously interrogate someone. My parents wouldn't stop hammering away at me with questions as I was heading out the door—I thought I'd never be able to leave! Would you stop hammering away at me with questions? I don't know where he is!
hammer away at
Keep at something continuously, as in The reporters hammered away at the candidate. This phrase employs hammer in the sense of "beat repeatedly," a usage dating from the mid-1600s.