The group, which also will be advised by David Plouffe and other top political aides to Mr. Obama, reflects the evolution in the president’s view on the intersection of money and politics. A year ago, facing the prospect of a financial disadvantage against Republicans in his re-election bid, Mr. Obama reversed himself and gave his blessing to a “super PAC” supporting his campaign.

Organizing for Action, which will be tax-exempt, can draw upon unlimited donations to take advantage of a muscular campaign apparatus that includes millions of Obama supporters. The group is planning to run television advertisements in a campaign-style effort to push the president’s initiatives.

“It’s not focused on politics,” Mr. Messina said. “It’s on supporting the legislative agenda.”

In previous administrations, similar tasks would have been performed by the White House Office of Political Affairs or the Democratic National Committee. But an outside group allows the operation to raise money, broadcast television ads and essentially run a political campaign on issues without running afoul of government guidelines that prohibit directly advocating for legislation.

Organizing for Action will be set up under Section 501(c)(4) of the tax code, the federal designation for “social welfare” groups that are dedicated to advancing broad community interests. The government does not require the disclosure of donors, although Mr. Messina said the group would voluntarily disclose its sources of financing but not impose contribution limits. Aides said they were uncertain whether the amount of specific donations would be revealed.

“We have a remarkable opportunity right now to change our country,” Mr. Messina said in a message to supporters on Friday. “And if we can take the enthusiasm and passion that people showed throughout the campaign and channel it into the work ahead of us, we will be unstoppable.”