Facing an energized Republican Party and deep-pocketed conservative groups, President Obama is kicking off his 2012 reelection campaign with a concerted push for help from wealthy donors and liberal groups unbound by spending limits.

The strategy — which could begin in earnest as early as Monday with the formation of an official presidential committee — suggests a notable shift in emphasis for a president who has long decried the outsize role of money in politics.

Obama frequently points with pride to the role that smaller donors played in his 2008 election, when his campaign also openly discouraged spending by outside organizations. But now Obama finds himself seeking out the kind of big-money donations he has often criticized while encouraging independent groups to raise and spend unlimited money on his behalf.

Obama’s campaign manager-in-waiting, Jim Messina, has asked the party’s biggest supporters to raise $350,000 each this year, to be shared by Obama’s campaign and the Democratic National Committee, far higher than goals set during the 2008 cycle.

The effort could yield $140 million or more by the start of 2012, a pace likely to provide a major advantage to Obama and his party over potential GOP rivals. By comparison, Republican challenger Mitt Romney has set a minimum goal of $50 million for the primaries, though GOP strategists expect him to raise more.

The official start of Obama’s Chicago-based campaign is expected this week with an announcement to supporters and the filing of paperwork with the Federal Election Commission, advisers said. That will be followed by a whirlwind of major fundraisers scheduled later this month in Chicago, New York and California focused on both wealthy and middle-class donors.

With the 2012 presidential contest shaping up to be the most expensive political race in U.S. history, Obama last week traveled to New York to ask for help from dozens of wealthy Democrats. The first stop was the trendy Red Rooster Harlem restaurant, which played host to a 50-person, $30,800-a-head fundraising dinner for the DNC. Then it was off to the nearby Studio Museum for a thank-you reception with about 250 loyal donors, aimed at lining up support for the 2012 campaign.

“The dinner will be no more than 6 tables so that the President has time to spend at each table,” organizers noted in an e-mail message to attendees.

Senior Democratic aides say the early push among wealthy contributors makes sense given the lack of a primary race to inspire small donors. But DNC spokesman Brad Woodhouse said the campaign also will reach out to a broad group of potential contributors, including an aggressive use of Facebook, Twitter and other social media.

“Small donors, grass-roots donors, medium-sized and major donors were all part of the mix in 2008, and they will be again in 2012,” Woodhouse said. “We didn’t rely on one type of donor then, nor will we now.”

Democratic strategists say the aggressive fundraising goals are aimed in part at intimidating Republican rivals, who bested Democrats in overall political spending in 2010. The effort is expected to be bolstered by an outside group, now in the planning stages, headed by former White House aides Bill Burton and Sean Sweeney, advisers said.

“This president is quite strong, and already has a very developed list of supporters from the previous time,” said Richard Danzig, the Clinton administration Navy secretary who helped raise more than $500,000 for Obama in 2008. “He has all the advantages of being an incumbent.”

Yet the race is dogged by fears among supporters that Obama may not be able to match the historic fundraising juggernaut of 2008, when the candidate brought in nearly $750 million, much of it from small contributions solicited online. Some backers worry that a limping economy and disaffection among liberal activists and Wall Street donors could dampen Obama’s fundraising ability this time around.

“It’s a different climate,” said one longtime donor who, like many others, spoke on the condition of anonymity in order to talk frankly about the challenges facing the campaign. “The donor community has been disengaged from the White House.”

Republicans also criticize Obama for setting such lofty fundraising goals while in office: “Between the domestic and international crises currently facing the country, the president should demonstrate leadership for our country, not just his party,” said Republican National Committee spokesman Sean Spicer.

Obama’s senior advisers and many of his biggest financial supporters are optimistic, saying he should have little difficulty matching his 2008 fundraising record. At the same time, backers say, Obama will continue his efforts to limit the influence of special interests, again refusing to accept donations from corporate political-action committees or registered lobbyists. He also will urge outside groups to disclose their donors, aides said.

Peter Buttenwieser, a Philadelphia education consultant who helped raise more than $500,000 for Obama in 2008, said, “Once things get rolling and people take a look at the options, the campaign will raise all the money it needs.”

Since 2008, when Obama shattered records for online campaign donations, he has frequently cast himself as having reshaped politics by relying more heavily on average Americans than the super-wealthy. He told CNBC earlier this year that “the vast majority of the money I got was from small donors all across the country.”

That depends on the definition of “small”: About a third of the money he raised during the general election campaign did come from donors who gave $200 or less, a notably larger proportion than previous races, according to the Campaign Finance Institute think tank. But about 42 percent of the money came from donors giving $1,000 or more.

Obama also formed a group of “bundlers” who collected checks from their friends and earned special access to him and his staff, just as previous candidates of both parties had done before, and he declined public financing to avoid spending limits.

Some Democratic donors and campaign experts say the millions of middle-income people who donated to Obama three years ago may not have the motivation to give again. The 2012 campaign will lack the combination of factors that animated the 2008 contest: a fresh-faced candidate who could be the first black president; polarizing opponents like Hillary Rodham Clinton and Sarah Palin; and the eagerness of Democrats to end Republican control of the White House.

“He begins the race with the biggest donor base in presidential history, but you also have to add the dimension that it will be hard to replicate the historic nature of his candidacy,” said Anthony Corrado, a campaign-finance expert at Maine’s Colby College.

Obama also will be hobbled by rocky relations with the business community and softer support among some liberals.

“His refusal to fight Republicans or Wall Street corporations has left small-dollar donors much less inspired than in 2008,” said Adam Green at the Progressive Change Campaign Committee.

The president himself has acknowledged he may face a deficit in enthusiasm, one that he is urging supporters to overcome.

“Obviously the first time around it’s like lightning in a bottle,” Obama said at a recent DNC reception in Washington. “There’s something special about it, because you’re defying the odds. And as time passes, you start taking it for granted that a guy named Barack Hussein Obama is president of the United States. It’s not.”

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