WASHINGTON (AP) — President Barack Obama's campaign is asking top fundraisers to support a Democratic-leaning outside group that is backing the president's re-election bid, reversing Obama's opposition to "super" political action committees, which can spend unlimited amounts of cash to influence elections.

Obama's campaign urged wealthy fundraisers in a Monday night conference call to support Priorities USA, a super PAC led by two former Obama aides that has struggled to compete with the tens of millions of dollars collected by Republican-backed outside groups.

Obama has opposed the Supreme Court's 2010 Citizens United decision that stripped away some limits on campaign contributions. The new super PACs can't coordinate directly with campaigns, but many have played a major role in the Republican primary contests, raising millions of dollars to use in negative advertising in early contests such as Iowa, South Carolina and Florida.

Obama campaign manager Jim Messina said in an email to supporters Monday that the president's campaign "can't allow for two sets of rules" in which the Republican presidential nominee benefits from "unlimited spending and Democrats unilaterally disarm."

"We decided to do this because we can't afford for the work you're doing in your communities, and the grassroots donations you give to support it, to be destroyed by hundreds of millions of dollars in negative ads," Messina said.

Messina said senior campaign officials, along with some White House officials and Cabinet members, would attend and speak at fundraising events for Priorities USA but would not directly ask for money. He said Obama, Vice President Joe Biden and first lady Michelle Obama would not be part of the effort and would remain focused on Obama's campaign.

The decision to promote the outside Democratic group came after new fundraising reports revealed a large disparity against Republican super PACs. American Crossroads and Crossroads GPS, two groups tied to Republican strategist Karl Rove, raised $51 million last year while major Democratic groups, including Priorities USA Action, collected $19 million last year.

Democrats have raised concerns about the potential of the super PACs to dominant the airwaves with negative advertising in the general election. Obama campaign senior strategist David Axelrod told reporters last month that the "prospect of hundreds of millions of dollars of negative ads raining down on us is not a prospect that I relish." But he said then Obama was "thoroughly known to the American people" and would be less susceptible to an onslaught of tough ads.

Underscoring the concerns, the first ad aired by the Obama campaign defended the president's record on energy and ethics. It came in response to a hard-hitting ad aired by Americans for Prosperity, a group connected to billionaires Charles and David Koch, that accused the president of using taxpayer money to benefit political donors at bankrupt energy company Solyndra.

Republicans criticized the Obama campaign's embrace of the outside groups, calling it a hypocritical shift by Obama after he chided the influence of secret, special-interest money. Obama has previously referred to the money as a "threat to our democracy."

"This is a brazenly cynical move by Barack Obama and his political handlers, who just a year ago had the chutzpah to call outside groups a threat to democracy," said Jonathan Collegio, a spokesman for American Crossroads.

The super PACs have played a major role in the primary contests. 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.

The group supporting Mitt Romney, Restore Our Future, collected $17.9 million in contributions since July, most of which it spent on advertisements supporting Romney or attacking Republican rival Newt Gingrich. A pro-Gingrich group, Winning Our Future, received $11 million from the family of casino mogul Sheldon Adelson.

The new super PACs can't coordinate directly with campaigns, but many that are active in this election are staffed by longtime supporters or former aides of the candidates.

Obama's campaign also said Monday it is returning about $200,000 in contributions collected by family members of a Mexican casino owner who fled the U.S. after facing drug and fraud charges.

The campaign said it had decided to return the donations arranged by Chicago brothers Carlos Cardona and Alberto Rojas Cardona, who had begun raising money for the campaign and the Democratic National Committee last year.

The New York Times reported late Monday that the fundraisers are the brothers of casino owner Juan Jose Rojas Cardona, who skipped bail in Iowa in 1994 and has since been linked to violence and corruption in Mexico.

The campaign said it refunded the money raised by family members after the newspaper asked about the brothers' fundraising role. Obama campaign officials said they were identifying donations bundled by other people connected to Cardona, expected to be about $100,000, and would return those funds as well.

"On the basis of the questions that have been raised, we will return the contributions from these individuals and from any other donors they brought to the campaign," said Obama campaign spokesman Ben LaBolt.

The newspaper reported that Gordon Fischer, a lawyer and the former chairman of the Iowa Democratic Party, had sought a pardon for Juan Jose Rojas Cardona from Iowa Gov. Chet Culver, a Democrat, but none was granted.