By Alina Selyukh
WASHINGTON (Reuters) - Millions of dollars were raised and spent, swing states reeled from endless political ads, and now that President Barack Obama has been re-elected, the soul searching begins.
What happened to the powerful Republican "Super PACs" and advocacy groups that staked all in a failed attempt to ensure the Democrat's defeat?
The 2012 campaign was the first real test for "super" political action committees (PACs) - in part spawned by a 2010 U.S. Supreme Court ruling known as "Citizens United" that did away with limits on corporate and union spending in elections.
Campaign finance reformers on the left had feared the change in the law would give Republicans an advantage.
Democrats were initially reluctant to embrace Super PACs, in part out of squeamishness, having resisted such unfettered campaign funding by big business. However, faced with the massive amounts of money being spent on the other side, they eventually came around and contributed enough cash to their own Super PACs to put up a successful fight.
Conservative Super PACs say they did all they could to help Republican Mitt Romney stand up to Obama's well-oiled campaign fundraising machine that ensured his early and dominant presence on the airwaves.
Indeed, more than a dozen free-spending groups spent nearly half a billion dollars propping up Romney's run, first helping him float to the top in the Republican nomination and then sustaining him through a money gap in the summer.
But in the end, the unprecedented $6 billion spent on this election - a grand total by campaigns and outside groups in the primary, congressional and presidential races, with one-sixth of that funding presidential advertising alone - became so excessive that impact of the ads waned. Experts say this proved the importance of the candidate's own activity and once again rendered successful a strategy of leveraging the power of incumbency to define the challenger early in the race.
In an email to supporters shortly after his victory on Tuesday night, Obama thanked his grassroots organizers, and said: "Today is the clearest proof yet that, against the odds, ordinary Americans can overcome powerful interests."
But the Democrats also made good use of the new system.
The main pro-Obama Super PAC, Priorities USA Action, repeatedly hit out against Romney, painting him as a corporate raider. One ad went as far as to link his former employer, Bain Capital, to the death of a laid-off worker's wife.
Priorities USA Action reported investing nearly $70 million into digital, TV and radio advertising, federal disclosures show.
And despite its squeaky start as Democrats took time to warm to the notion of Super PACs, the attacks on Romney went largely unanswered. Bill Burton, who runs Priorities, has called this "one of the biggest surprises in the entire election," and in private, Republican operatives also acknowledge that it was a big disappointment.
"They missed the most important role they could have had - saving Romney's back when he was being attacked," Burton said of rival groups, such as the pro-Romney Restore Our Future and the formidable Crossroads duo of Super PAC and non-profit run by former George W. Bush aide Karl Rove.
The two Crossroads groups spent nearly $150 million on advertising in the presidential race, according to tallies provided by Republican sources. Tax-exempt groups are not required to officially disclose all of the spending or donors.
Restore Our Future has reported spending nearly $100 million on creating and placing ads, according to federal disclosures.
Of course, Priorities' ads alone did not cost Romney the election, but they showcase what Republican Super PAC operatives have called the dichotomy in strategic approaches to the race: Democrats got vitriolic and personal, while top Republican groups largely steered clear of attacking Obama personally or even talking of Romney individually, instead sticking with broad partisan messages on the economy and policies.
Republican strategists say that personal attacks were avoided because they got poor reviews from independents and women, cohorts they had hoped to sway in Tuesday's election.
But the broader focus stems also from the fact that the sights of leading conservative groups are set far beyond Romney and 2012 -- on the pursuit of a lasting Republican majority in the Congress, a buildup of boots-on-the-ground power to challenge the Democrats' advantage and popularization of conservative economic or social values.
"It's never about one year or one election; it genuinely is about bringing the public to our view," said Tim Phillips, president of Americans for Prosperity, a conservative non-profit that has pursued a major expansion of the Republican ground game, in part funded by the billionaire Koch brothers.
"That's not our job," Phillips said about the lack of response to attacks on Romney, echoing what leaders of allied groups said. "They have campaigns and parties to do that."
Americans for Prosperity spent around $46 million airing presidential TV ads, according to tallies by Republican media trackers.
'FIGHT THE GOOD FIGHT'
According to Reuters/Ipsos polling, nearly three-quarters of Americans had made up their minds in the presidential race before Obama and Romney faced off in the first debate on October 3.
That puts much value on the campaigning done in the summer, when Obama's team had the traditional incumbent's advantage in the money race: Although Romney outraised Obama several months in a row, he was not allowed to use much of the cash until his nomination at the party convention in late August.
Getting a head-start in the race, Obama poured large chunks of cash into massive grassroots investments and blanketed the airwaves with early ads, which cost him far less than what Romney had to spend trying to match the placements last-minute.
That's when the pro-Romney Restore Our Future faced its raison d'etre, according its founder, Charlie Spies.
"Our strategy was to fill in the gap before the convention and we thought that if we ended up spending all of our money, coming out with not a penny to our name, we would have done a service," he said.
In many ways, the Democrats' tactics were generously borrowed from Republicans' own playbook from 2004, when President Bush's re-election campaign hit early against Democratic challenger John Kerry, eventually sailing to a win, despite the then-record amounts spent by liberal outside groups.
And like Democrats at the end of 2004, despite the ultimate loss, Republican Super PAC strategists now seek solace in arguing that they succeeded in suppressing Obama's early surge.
"Donors, they know that it is crucial to fight the good fight and that's certainly been done," Phillips of Americans for Prosperity said.
Among the super-rich who may be wondering whether their money was well spent are casino mogul Sheldon Adelson, Houston homebuilder Bob Perry and Dallas banker Harold Simmons.
For those who keep faith, the fight is far from over: While the fate of Restore Our Future - which is tied to Romney personally - is unclear, Americans for Prosperity and Crossroads strategists say they plan to shift gears quickly to promoting conservative policies in this year's looming budget debate.
Phillips said Americans for Prosperity plans to retain many of its grassroots organizers would push to "mitigate the damage that the president will do in the next four years" in battles over the fiscal deficit, healthcare overhaul and tax cuts.
(Additional reporting by Alexander Cohen; Editing by Claudia Parsons and David Brunnstrom)