WASHINGTON (AP) — President Barack Obama's re-election effort enjoyed a 10-to-1 financial edge over Republican rival Mitt Romney last month, out-raising the former Massachusetts governor by millions as Obama stuffed more than $104 million into his campaign war chest.

A nasty primary battle between Romney and his GOP rivals took a financial toll on his presidential campaign, which raised $12.6 million in March and left Romney with about $10 million in the bank by month's end. All told, Obama and the Democratic Party raised a combined $53 million in donations during that period, while Romney with his party pulled in about half of that.

Still, an anticipated fire hose of cash from major Republican "super" political committees and the Republican Party is likely to bring some financial parity to the general election, for which Romney only recently started collecting donations. Super PACs like American Crossroads and its nonprofit arm, Crossroads GPS, raised $100 million this election cycle, and the groups plan to flood the airwaves in coming months with ads critical of Obama.

Also helping Romney is the Restore Our Future super PAC, which reported an $8.6 million last month, largely from a handful of wealthy donors and some continued supporters. The group, for its part, spent more than $11 million on TV spots during the month, coming off a successful track record of battering Romney's GOP primary opponents with attack ads.

For the first time since Super Tuesday, voters got a look at just how much money presidential candidates and their supporters have been raking in. Friday marks nearly three months since Obama's campaign changed course and asked supporters to pony up cash to a favorable super PAC, although its fundraising figures weren't yet available late Friday.

Financial reports due Friday to the Federal Election Commission were expected to show much red ink struggling campaigns are bleeding — or how much money some groups have been stuffing into their war chests. The Republican National Committee reported a March fundraising haul of $13.7 million, which will boost the eventual GOP nominee during the general election.

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Obama's fundraising advantage puts him at a less-than-solid position when compared with the tens of millions of dollars the sister Crossroads groups have amassed so far. During the last six months of 2011 alone, GPS brought in $28 million from only a few dozen major donors, recent tax filings show. Crossroads has said it plans to raise more than $300 million to beat Obama.

Countering Crossroads' millions in ad spending is Priorities USA Action, a super PAC founded by former Obama advisers. From early 2011 through the end of February, however, the group and its nonprofit arm raised about $10 million. Priorities USA Action, like other super PACs supporting GOP candidates, has counted on major financial support from a handful of wealthy donors.

But Obama, for his part, is facing the prospect of being swamped by outside Republican groups in fundraising. That's why he decided to reverse course and give his blessing to super PACs, which can accept unlimited donations from corporations, labor unions and wealthy individuals.

On the Republican side, those outsized donations come from generous donors like Las Vegas casino magnate Sheldon Adelson and his wife, who have given more than $10 million combined to a super PAC supporting Newt Gingrich. In March, however, only his wife, Miriam, contributed to the Gingrich-supportive Winning Our Future PAC; she gave $5 million.

The largest March contribution to Restore Our Future was $1 million from Huron Carbon LLC, a firm based in West Palm Beach, Fla. The company's owner is not revealed in the super PAC files, but it shares a street and suite address with Oxbow Carbon LLC, a fossil-fuel processor and mining firm headed by energy magnate William Koch. Regulatory filings also show a similarly named Canadian firm, Huron Carbon, with ties to Great Lakes Carbon, a company bought by Oxbow in 2007.

Oxbow had previously given $750,000 to the pro-Romney committee and Koch made an earlier personal contribution of $250,000. Koch is a brother of wealthy GOP donors Charles and David Koch, and while William Koch also supports many GOP causes, he has also at times supported Democrats. Oxbow is a fossil fuels processor and mining operation that has pressed for changes to laws and regulations on mining, safety issues and climate change.

Richard and J.W. "Bill" Marriott, hotel industry magnates whose family is close to the Romneys, also contributed $250,000 apiece to the pro-Romney group. For both men, the donations raised their total gifts to the super PAC to $1 million each. Kenneth C. Griffin, 43, a Chicago hedge fund director, also gave $750,000 to Restore Our Future, following up on $200,000 in earlier donations to the PAC.

The financial reports reflected how much has changed since the March 6 Super Tuesday contests, when Republican voters in six out of 10 states chose Romney as their preferred nominee to compete against Obama. Rick Santorum has since folded his campaign, and Gingrich has been working with a shoestring budget.

Gingrich, who has vowed to continue his floundering campaign, racked up more than $4 million in outstanding debt by the end of March, reports show. He raised less than half of that — about $1.7 million — during the same period.

Expenses in Friday's filings also showed some disparity between the two frontrunners' staff sizes, with Obama paying more than 600 and Romney fewer than 100. But that number is expected to grow sizably as Republican donors contribute more to Romney's effort.

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Associated Press writer Stephen Braun contributed to this report.

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