Only around 125,000 voters caucused in Iowa Tuesday, but millions were subjected to a flurry of often blistering television ads leading up to caucus day.

Between the media spending from individual campaigns to the loads of spending from Super PACs, Iowa is just the beginning. This election cycle is the first presidential contest since the Supreme Court’s Citizen's United decision, which sparked the formation of a flurry of Super PACs expected to collectively dump hundreds of millions of dollars into this year's presidential election.

“I believe it’s a game changer, and I just look to what has happened to Newt Gingrich in the last couple of weeks,” says Trey Grayson, director of the Harvard Institute of Politics.

After the former House Speaker surged late in a volatile pre-caucus scramble, he was subjected to a withering assault on the airways, largely funded by a Super PAC supporting former Massachusetts Gov. Mitt Romney. Gingrich sunk fast and ended up with a fourth place finish on caucus night. 

Without a formidable fundraising arm Gingrich appeared desperate, continually lashing out at Romney over the negative ad assault and even went so far as to call Romney a liar. Gingrich and his aides maintain they’re merely being honest about Romney’s record.

“What the Romney guys don’t understand is that our capacity to tell the truth outlasts their capacity to spend money,” according to Gingrich spokesperson R.C. Hammond who contends that Romney “hides behind super PACs.”

It's a clear sign of what's to come in the general election as Super PACs on the left and the right prepare to drive the message and will very likely control more money than the national parties.

The other advantage evident in the battle for Iowa, says Bill Allison of the Sunlight Foundation, is the willingness of candidates to sit back and let Super PACs do much of the dirty work for them, even though they are legally barred from coordinating.

“It gives candidates the plausible deniability of being able to say, ‘Hey, I’m not going negative, I’m running a very positive campaign.’ And yet the former treasurer of your campaign is running ads that are trashing your opponents,” says Allison. 

The nastiness of primary squabbles certainly isn't new, but the sheer amount of negative advertising and money this early in the process is unlike past nominating contests.

“It’s not as if we haven’t seen negative ads run by outside groups. We’ve never seen this many or this much spending,” contends Allison. “These groups are kind of coming out of the woodwork and it seems like there is a new one almost every day that is announcing and then running ads.”

Nearly $13 million dollars has been spent so far in Iowa and other early voting states by super PACS, according to the Center for Public Integrity. And Romney was the biggest benficiary in Iowa. The Restore Our Future PAC spent $4.6 million on his behalf on anti-Gingrich advertisements.

Texas Gov. Rick Perry received the second most assistance, garnering $3.7 million from the Make Us Great Again PAC. He stumbled to a fifth place Iowa finish.

Gingrich himself received around $900,000 in supportive TV ads from Winning Our Future, though it was too little too late. And analysts contend the results might have been different in Iowa had former Pennsylvania Sen. Rick Santorum peaked earlier. Santorum came on so late that it proved a struggle to get new attack ads out against him, and there was little chance to buy the airtime, either. Santorum did get hit with a barrage of negative-robocalls – some Iowa voters report getting as many as seven negative calls on Monday alone.

But Santorum was able to withstand the last minute barrage in part because he had spent so much face time with social conservative voters in the past year, proving retail politics is still alive and well. Given Santorum’s showing in Iowa, he's now bracing for a similar onslaught as the battle for the nomination moves on to New Hampshire, South Carolina and Florida.

“The story that will be written at the end of the 2012 [elections] is the role of the super PAC,” says Brian Dumas, president of Victory Enterprises, an Iowa-based consulting firm. “I think it is only going to be magnified in the general election. The super PACs will control the messaging of the campaigns and will ultimately, I think in this election cycle, have a greater sway on Election Day then what the individual candidates do."