If the Wisconsin recall battle was a test of the power of political spending, the big money won big.

Republican Gov. Scott Walker, who survived an effort by the state’s Democrats to unseat him in a special election on Tuesday, outspent his opponent by more than 7 to 1 and easily overcame massive get-out-the-vote efforts by Democrats. The recall contest ranks as the most expensive race in Wisconsin history, with the candidates and interest groups spending more than $63 million combined.

Walker was bolstered by wealthy out-of-state donors who gave as much as $500,000 each under state rules that allow incumbents to ignore contribution limits in a recall election. He raised $30.5 million, while his Democratic challenger, Milwaukee Mayor Tom Barrett, raised $3.9 million, according to data compiled by the Wisconsin Democracy Campaign.

The big spending was made possible in part by the landmark Supreme Court decision in Citizens United v. Federal Election Commission , which allowed corporations and unions to spend unlimited amounts on elections and made it easier for wealthy individuals to bankroll such efforts. Wisconsin is among a number of states that previously banned direct election spending by corporations and labor groups.

As a result, many Democrats and campaign watchdog groups see the Badger State matchup as a test run of sorts for November, when super PACs and other interest groups could spend $1 billion or more on political ads and organizing efforts in races for the White House and Congress. The outcome also has prompted hand-wringing on the left over whether pro-Democratic groups, which traditionally focus on ground-game organizing rather than advertising, will need to rethink their strategy.

“The Wisconsin results should serve as a wake-up call for Democrats: On-the-ground organizing is critically important, but it must be coupled with an aggressive air campaign,” said Rep. Steve Israel (N.Y.), chairman of the Democratic Congressional Campaign Committee. “The election is about who you are for — big corporations, Big Oil, and millionaires or the middle class. Without robust air cover, the voice of the middle class will be silenced.”

But not everyone agrees that loosened campaign finance rules had much to do with the result in Wisconsin. Exit polling suggested that most voters had decided whom they would support in the contest by April — before the main onslaught of ad spending — and labor unions and other pro-Democratic interest groups were able to match expenditures by Republican groups outside the Walker and Barrett campaigns.

Bradley A. Smith, a former FEC chairman who heads the Center for Competitive Politics, which generally opposes contribution restrictions, said in a statement that unlimited fundraising by outside groups actually helped Barrett by allowing his side to narrow the spending gap. The fact that Walker could raise unlimited contributions suggests that other politicians should have the same freedom, he said.

Finally, Smith said, “the high turnout in yesterday’s election suggests that, contrary to what some try to claim, high spending did not discourage people from voting, but perhaps encouraged turnout.”

Unlike Walker, Barrett could collect checks of up to only $10,000 for his challenge. Many of Walker’s top supporters were active GOP mega-donors from other states, including Houston home builder Bob Perry ($490,000); Las Vegas casino magnate Sheldon Adelson ($250,000); and billionaires Louis Bacon of New York and Trevor Rees-Jones of Texas, both of whom gave $100,000.

The governor’s biggest single supporter was Wisconsinite Diane Hendricks of ABC Supply Co., who donated $510,000, records show.

Proponents of tighter restrictions on political spending say the Wisconsin election underscores the need for reform, whether through an expanded public financing system for elections or a constitutional amendment aimed at overturning Citizens United.

“This is just another example of big money winning,” said David Donnelly, executive director of the Public Campaign Action Fund, which favors a public financing system for elections. “The strategic question is whether we just have people complain about it, or are we going to fix some of these problems in our campaign finance laws? We need a serious, comprehensive plan to add a little democracy to our democracy.”

Richard L. Hasen, an elections law specialist at the University of California at Irvine, said that Citizens United is “a convenient scapegoat” but that “it’s hard to see it as the culprit” in the Wisconsin contest. He noted exit poll results suggesting that a large portion of pro-Walker voters opposed the recall process on principle.

“There certainly was a disparity between the money raised on the pro-recall versus anti-recall side, but I don’t think there was any question that those mounting the recall got their message out,” Hasen said. “I’m not convinced that if there was less disparity it would have closed the gap between Walker and Barrett in the results.”