Update: The full list of donors to the Super PAC is here, but that filing does not list the greater amount donated to the nonprofit.

WASHINGTON (AP) — American Crossroads, the Republican "super" political committee that plans to play a major role in this year's presidential campaign, raised more than $51 million along with its nonprofit arm last year, The Associated Press has learned.

The figures from Crossroads — the group backed by former George W. Bush adviser Karl Rove — were among the first financial reports being made public Tuesday, the deadline for super PACs and presidential candidates to file financial reports with federal election officials.

While most recent public attention has focused on groups spending major sums for negative TV ads assailing GOP presidential primary rivals Mitt Romney and Newt Gingrich, Tuesday's figures are a sign of even greater spending to come in the general election battle between the Republican nominee and Democratic President Barack Obama.

Other big Super PACs required to disclose their donors Tuesday include Restore Our Future, the Romney-leaning PAC that has contributed to a deluge of ads hammering Gingrich, and Winning Our Future, the Gingrich-supportive group that has been critical of Romney's time at a venture capital firm. Both super PACs are run in part by former advisers to the candidates.

The American Crossroads PAC has about $15.6 million cash on hand, representing only part of the money it has in the bank to spend on defeating Obama. Financial details from Crossroads GPS — the nonprofit arm — are unclear because it doesn't have to disclose its donors under IRS rules, althoughCrossroads GPS was responsible for most of the groups' fundraising haul.

The Crossroads war chests underscore the extraordinary impact Super PACs could have on this year's race for the White House. In GOP primaries so far, groups working for or against presidential candidates have spent roughly $25 million on TV ads — about half the nearly $53 million spent on advertising so far to influence voters in the early weeks of the race.

Crossroads' financial reports, which the AP obtained ahead of the Federal Election Commission, identify wealthy donors who had given contributions reaching as high as seven figures by the end of 2011. Among the largest contributors is Dallas businessman Harold Simmons, who gave the group $5 million last November and whose holding company, Contran Corp., donated an additional $2 million.

Simmons is a major donor to GOP and conservative causes who pumped as much as $4 million into the "swift boat" campaign that helped sink Democratic presidential nominee Sen. John Kerry in 2004. Simmons, an early supporter of Texas Gov. Rick Perry's presidential run, also was a fundraising "bundler" putting donations together for Arizona Sen. John McCain.

Other Super PACs have already had a major effect this primary season. One group, for instance, effectively saved Newt Gingrich's candidacy, while another tore into him in Florida and elsewhere. At the minimum, the groups' spending is a precursor to the general election — when super PACs aligned with both Republicans and Obama plan to dole out even larger sums.

These groups are the products of a 2010 Supreme Court ruling that removed restrictions on corporate and union spending in federal elections. The groups can't directly coordinate with the candidates they support, but many are staffed with former campaign workers who have an intimate knowledge of a favored candidate's strategy.

Since this summer, the groups have spent tens of millions on ads in key GOP primary states like Iowa, New Hampshire, South Carolina and Florida. The PACs have also unleashed millions on expenses typically reserved for campaigns, including direct mailings, phone calls and get-out-the-vote efforts.

Few groups are likely to be as influential as American Crossroads, which plans to raise hundreds of millions of dollars this election cycle and enlists support from high-profile GOP figures such as former Mississippi Gov. Haley Barbour.

Crossroads' financial reports show other large donors such as Joseph W. Craft III, a Tulsa businessman whose Alliance Holdings, a major coal producer, gave $425,000. Other contributions include: $500,000 from Dallas-based Crow Holdings; $250,000 from Chicago philanthropist and GOP supporter Janet Duchossois, and $100,000 from Sam Zell, a Chicago real estate billionaire whose Tribune media company is now in bankruptcy.

Outside spending by individuals isn't new. Liberal-leaning billionaire George Soros gave more than $20 million to help groups supportive of Kerry — these groups were known as "527" organizations — and his 2004 White House bid. But the high court's Citizens United ruling essentially gave a green light to individuals who want to pump unlimited sums into outside groups that would in turn support candidates.

The Obama campaign on Tuesday disclosed a list of 61 people who raised at least half a million dollars for the president's re-election efforts. Among them are movie producers Jeffrey Katzenberg and Harvey Weinstein and embattled former New Jersey Gov. Jon Corzine, whose $70,000 in contributions from himself and his wife were refunded by the Obama campaign and the Democratic National Committee.

A handful of other financial filings began trickling in to the Federal Election Commission Tuesday afternoon, including those from the Gingrich campaign. It said the former House speaker raised $10 million during the fourth quarter, in addition to $5 million this month. Those totals are separate from super PAC money being spent on his behalf by outside groups.

Perry, the Texas governor who was an early star in the Republican primaries, raised an anemic $2.9 million this past quarter, compared with $17.2 million within the first two months of his entering the race last summer. The Jon Huntsman-leaning Our Destiny super PAC raised about $2.8 million — with more than $1.8 million coming from his father, Jon Huntsman Sr.

Endorse Liberty, a group supportive of libertarian-leaning Rep. Ron Paul of Texas, said it raised $3.9 million for online advertising in key primary states.

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Associated Press writers Stephen Braun and Jim Kuhnhenn contributed to this report.