WASHINGTON -– Record spending by independent groups largely defined how the 2012 elections were fought, but the money had no discernible impact on the outcome of most contests, according to an early analysis of ballot results and expenditures by The Washington Post.

A clutch of conservative billionaires and privately held corporations fueled nearly $1 billion in spending by super PACs and nonprofit groups this cycle, unleashing a wave of attack ads unrivaled in U.S. history. Yet Republican groups and their donors failed to achieve their two overarching goals — to unseat President Barack Obama and return the U.S. Senate to the control of the GOP.

In the Senate, Republicans lost ground, pouring well over $100 million in outside money into a half-dozen seats that went to Democrats. In the presidential race, GOP nominee Mitt Romney and his allies spent more than twice as much as John McCain in 2008, but only took back red-leaning Indiana and North Carolina for their trouble.

Even in the House, where last-minute surges of cash would seem to stand a good chance of swinging races, GOP money groups struck out repeatedly, according to the Post analysis. In 26 of the most competitive House races, Democratic candidates and their allies were outspent in the final months but pulled out a victory anyway. That compares to 11 competitive races where Republicans were outspent and won.

Outside money was the dog that barked but did not bite. Obama and other Democrats had long made dire predictions about the potential impact of Citizens United vs. Federal Election Commission, the Supreme Court case which allowed corporations and unions to spend unlimited funds on elections and created an entirely new class of wealthy political groups.

The money did dramatically change the focus and character of many campaigns. Candidates up and down the ballot were forced to spend more time than ever raising donations, while political advertising funded by outsiders was even more negative than before. Wealthy donors were so central to Romney’s campaign that a swarm of private luxury jets caused a traffic jam at Boston’s airport just prior to the nominee’s Tuesday night election party.

“Its lasting impact will be that it fueled the public’s disgust about politics,” said David Donnelly of the Public Campaign Action Fund, which favors stricter campaign-finance regulations.

Yet super PACs and secretive nonprofit groups — which spent up to $10 million a day on the presidential race alone — couldn’t move the needle far enough to prevail in nearly any of the big races they targeted. Outside money allowed Romney to be competitive with Obama, but that meant the candidate had no direct control over much of the spending, while his own campaign was plagued by high personnel costs and lavish consulting fees.

In the end, the two sides reached a kind of dreary equilibrium, clogging the airwaves with so many attack ads that Republican groups began airing spots in California and other deep-blue states where they had little chance of victory. By the end of October, more than a million commercials had been broadcast in a presidential race that remained close to a dead heat for much of the year.

Indeed, if election investments are like the stock market, a lot of billionaires just lost their shirts. The two biggest pro-Republican groups, American Crossroads and Restore Our Future, together spent more than $400 million on federal races with relatively little to show for it in the end. Conservative groups tapped a wellspring of funds from energy executives, hedge fund managers and other financiers eager to oust Obama.

The most generous donors of all, Las Vegas casino magnate Sheldon Adelson and his wife, Miriam, funneled more than $53 million to groups backing Romney, GOP primary hopeful Newt Gingrich and other Republicans. Nearly every one of them lost.

“I think it shows that it’s not always about the money,” said Rodell Mollineau of American Bridge 21st Century, a small super PAC that spearheaded opposition research efforts for Democrats. “I don’t think the other side was always very efficient or smart in their spending. There was a lot of discombobulation.”