go negative

Verb

 * 1)  To focus on attacking political opponents rather than promoting oneself.
 * 2) * 2011, Judith S. Trent, Robert V. Friedenberg, Robert E. Denton (Jr.), Political Campaign Communication: Principles and Practices (page 235)
 * All four of the principle candidates in the 2008 presidential election “went negative” in their acceptance addresses.
 * All four of the principle candidates in the 2008 presidential election “went negative” in their acceptance addresses.