Verb
go negative (third-person singular simple present goes negative, present participle going negative, simple past went negative, past participle gone negative)
(US, politics) To focus on attacking political opponents rather than promoting oneself.
I don't want to go negative on Franklin Delano Roosevelt, but he didn't pass an economic deal in the first 100 days. We have passed the largest Recovery Act in the history of the country. Rahm Emanuel