The Republican candidates and a few independent groups have spent nearly $10 million on television and radio ads in seven states that vote on Super Tuesday, and more than half of that total comes from the Mitt Romney-backing Restore Our Future, which is running spots criticizing Rick Santorum and Newt Gingrich.

The infusion of cash into this coming week's contests has swelled total ad spending in the GOP presidential race to more than $75 million, according to a review of Federal Election Commission data and information provided to The Associated Press by several media buyers. About $40 million has been spent by the Romney campaign and Restore Our Future to support the former Massachusetts governor.

The latest figures provide more evidence of the oversized role that these groups, known as super political action committees, have played in the campaign.

Super PACs were spawned by a 2010 Supreme Court ruling that eased campaign finance regulations for corporations, unions and wealthy individuals. These groups can raise and spend unlimited funds as long as they do not coordinate directly with a candidate.

Restore Our Future, run by several former Romney advisers, is the top spender on TV ads, with more than $25 million; the vast majority has paid for ads targeting Romney's opponents. By comparison, the Romney campaign has spent about $14 million.

Super PACs have all but kept alive the candidacies of Santorum and Gingrich. Their campaigns have run on shoestring budgets as they jockey to be Romney's principal conservative challenger.

With 10 states set to hold primaries and caucuses on Tuesday, the Romney campaign and several super PACs are focusing primarily on the four considered most competitive: Ohio, Georgia, Oklahoma and Tennessee.

In Ohio, where polls show Santorum with a narrow lead, Romney's campaign has spent about $1.2 million on ads. One takes on Santorum for flip-flopping on whether he supported Planned Parenthood. That ad shows clips from a recent GOP debate, where the former Pennsylvania senator acknowledged voting to fund the organization even though he doesn't support the family planning organization.

"Sometimes you take one for the team," Santorum is shown saying.

Restore Our Future has spent twice that amount, $2.4 million, in Ohio on ads trashing Santorum, also going after him on that issue. "Santorum says he's the principled conservative. But that's not how he voted," one ad says.

Restore Our Future is spending just over $1 million to air ads in Tennessee and $500,000 in Oklahoma _ the largest ad buys in the two states.

The group has spent about $1.5 million in Georgia, Gingrich's home state and a must-win for the former House speaker. An ad tries to debunk Gingrich's claims that he worked closely with President Ronald Reagan; a similar ad aired earlier in the campaign in Florida.

Restore Our Future has slowed Gingrich's ascent in the race twice before: in Iowa, when his campaign surged into the lead before that state's first in the nation caucuses, and Florida, where a flood of negative ads from both Restore Our Future and the Romney campaign halted his momentum after his decisive triumph in South Carolina.

The Red, White and Blue Fund, a super PAC that supports Santorum, has spent about $3 million total on ads in the race. The group has spent about $514,000 on TV and radio ads in Ohio that criticize Romney for enacting a health care plan in Massachusetts similar to President Barack Obama's and bash Gingrich for lobbying for federal housing giant Freddie Mac.

"How can Mitt Romney or Newt Gingrich beat Barack Obama when on the vital decisions they're not much different?" the ad asks.

The Santorum campaign, by contrast, has just purchased a modest about of ad time on cable television in the four states.

The pro-Gingrich super PAC Winning Our Future has spent $2.6 million on radio and television ads in the four major Super Tuesday states, including nearly $1 million in Georgia alone. The group's TV ad includes clips of people saying they don't trust Romney and mocking him for his wealth.

"Romney's not the type to pump his own gas," a woman says in the ad.

Rick Tyler, a former Gingrich aide now a top official at Winning Our Future, acknowledged that Georgia is critical to Gingrich's future as a candidate.

"We're not worried about losing Georgia. But at the same time, he has to do well in Georgia," Tyler said. "Georgia is a lot like South Carolina, and Newt hasn't had a win since South Carolina."

Winning Our Future has been relying on money from Sheldon Adelson, a Las Vegas casino magnate who has contributed millions to the group since January and made an additional large donation this past week.

The Gingrich campaign has aired a half-hour infomercial on cable TV in the four major states Tuesday, where he outlined his plan to bring gas prices down and make the U.S. more energy independent. But the campaign hasn't purchased any broadcast time in Super Tuesday states.

Romney's campaign has bought cable advertising time in Idaho and Vermont, which also hold contests that day. Texas Rep. Ron Paul has also bought cable time in Vermont.

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Gillum reported from Washington. Associated Press writer Philip Elliott contributed to this story from Washington.

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