WASHINGTON — The barrage began in the second week of December, when Restore Our Future announced a $3.1 million television ad campaign in Iowa.

The Super PAC, a must-have in the monetary arms race of presidential politics, made an attack ad focused on Newt Gingrich’s post-Congress work for Freddie Mac and other controversies in ways the former House speaker says distorted his record.

The “avalanche,” as Gingrich put it after Tuesday night’s caucuses, helped send him to a fourth-place finish. The narrow winner was Mitt Romney, whose former campaign aides run Restore Our Future.

The results affirmed that Super PACs will play a big role in this year’s presidential election, having come of age since the controversial January 2010 Supreme Court decision legalizing them.

“Restore Our Future just flattened Gingrich,” said Dennis Goldford, a political science professor at Drake University in Des Moines, Iowa. “He’s right. If there were any doubts that negative ads work that was washed away, along with the Gingrich surge.”

In Thursday's newspaper, the AJC takes a deep look at the affect that Super PACs have already had on the 2012 presidential election. It's a story you'll get only by picking up a copy of The Atlanta Journal-Constitution or logging on to the paper's iPad app. Subscribe today.