"Attack ads" refer to political advertisements that aim to criticize or undermine an opponent by highlighting their weaknesses or negative qualities rather than discussing one's own strengths and policies. Full definition
She has third party attack ads on issues no one cares about. (nystateofpolitics.com)
The resort developers went as far as publishing attack ads in newspapers against you and the campaign. (goldmanprize.org)
I have to say that for me, living in a state that was ignored - i.e. not bombarded with attack ads for months at a time - would be highly desirable. (politics.stackexchange.com)