What does the word "hit job" mean? I found it in two different newspaper articles: "Russian athletics officials say Wada report is ‘a political hit job'" and "Ben Carson condemns 'political hit job' amid questions over personal story"

I guess it probably means something like "attack,""criticism," and "condemnation," but I'm not so sure. Could you tell me what exactly it means and where it comes from?
Yes. A hit job means an assassination. Here it is not used literally, but it would suggest an unfair attack deliberately designed to damage his reputation.
Assassination! I'm surprised.
Thank you very much indeed, Blue Jay.