According to a study by Kantar Media/CMAG, 6 percent of campaign advertising in the 2008 Republican primary were attacks on other members of the GOP. That number has shot up to over 50 percent for this election cycle, says the ad-tracking firm.
Additionally, so-called super PACs have spent 72 percent of their ad dollars on negative ads targeting other Republicans. The amount of negative ads from the campaigns themselves is only 27 percent.
Super PACs are forbidden by law from directly communicating with candidates, so negative ads are often their only recourse. “Super PACs are left with no good choices,” said Brad Todd, a veteran GOP ad man unaffiliated in this year’s contest. “if they didn’t run comparison or contrast ads, they would have some very boring television.”
Source: Washington Post