Negative campaigning is one term for this practice. It is also called mudslinging.

The idea is to point out flaws in ones opponent.

It is trying to win the advantage by referring to negative aspects of an oppenent or of a policy rather than emphasizing one's own positive attributes or preferred policy.

These are called attacks ads and are an example of negative campaigning.

Positive campaigning refers to political campaigns that focus on promoting a candidate's own strengths, accomplishments, and policy proposals, rather than attacking opponents. This type of campaigning aims to inspire and educate voters by emphasizing the candidate's positive attributes and vision for the future. It typically avoids negative attacks or mudslinging tactics against opponents.

Creative Campaigning was created in 1993.