In an advertisement for the film Blood Money, an action movie soundtrack builds in intensity while ominous phrases including Illegal activity and the Cayman Islands flash over images like a pair of hands shuffling through hundred dollar bills. The spot ends with the sound of a pulsing heart.

It may sound like a trailer for a Jerry Bruckheimer movie, but the advertisement -- an attack on Mitt Romney orchestrated by the pro-Newt Gingrich Super PAC Winning Our Future -- illustrates a surge in vicious advertisements during the 2012 Republican presidential primary.

Advertisements in which Republican presidential candidates attack their rivals for the nomination have soared this year, according to the Washington Post. The Post cites the ad-tracking firm Kantar Media/CMAG's finding that spots bashing other Republicans have made up the majority of ads during the 2012 primary. In 2008, such advertisements accounted for 6 percent.

The surge in internecine advertising warfare has accompanied the rise of Super PACs, entities that are legally allowed to raise unlimited amounts of money. While the law forbids candidates from coordinating with Super PACs, it is no secret that every candidate is allied with a particular Super PAC: just as those wishing to help out Gingrich can write a check to Winning Our Future, Mitt Romney supporters can offer a contribution to Restore Our Future.

Much of that money goes to advertising. The New Yorker's Jane Mayer reported that $15 million of the $17 million spent so far by Restore Our Future has gone to advertising. According to the Washington Post, super PACs have spent 72 percent of their money on negative ads, compared to 27 percent for campaigns.

In a telling indicator of the climate, Rick Santorum's campaign (not his Super PAC) ran an advertisement, entitled Rombo, in which a deranged-seeming Romney look-alike fires mud at a cutout of Santorum.

Mitt Romney's negative attack machine is back on full throttle, the narrator intones, noting that Romney and his Super PAC have directed a staggering amount on attacking fellow Republicans. The voiceover then goes on to attack Romney for supporting Massachusetts' universal health care law and cap-and-trade legislation.

And in the end, the narrator concludes as a jammed gun squirts mud onto Romney's shirt, Mitt Romney's ugly attacks are going to backfire.