The scandal has tarnished the candidate's 'halo'. [=has damaged his reputation as a morally good person]
the child's 'halo' of golden curls
(..) for the lab that may still work. It's no good. - Let me try mine. John! Fire-in-the-hole! Wait! You can't go in there! The fire's set off the halo system ! You have to wait a few minutes, until the gas clears. Put this on. Alright, let's get to work. All units in the vicinity. (..)1991 Terminator 2: Judgment Day