A candidate's shelling of an opponent often ricochets back on himself. A classic example was the 1998 "murder-suicide" — a characterization coined by Davis strategist Garry South — when gubernatorial aspirant Al Checchi destroyed both his and Rep. Jane Harman's candidacies with relentless attack ads.

Checchi once claimed he'd rather lose the election than ''go negative.'' But he never said what he'd do if he fell behind in the polls. When he did, he went negative with a vengeance first against Harman and then against Davis. … A second apparent unintended consequence of Checchi's anti-Harman advertising blitz was creating an opening for the underfinanced seeming also-ran Davis, who vaulted past Checchi in the polls as Harman was falling behind.

''Basically, what you have here is a murder-suicide,'' said Davis campaign manager Garry South. ''Checchi killed Jane Harman, but the collateral damage from those attacks killed him.''