WASHINGTON — President Obama is signaling to wealthy Democratic donors that he wants them to start contributing to an outside group supporting his re-election, reversing a long-held position as he confronts a deep financial disadvantage on a vital front in the campaign.

Aides said the president had signed off on a plan to dispatch cabinet officials, senior advisers at the White House and top campaign staff members to deliver speeches on behalf of Mr. Obama at fund-raising events for Priorities USA Action, the leading Democratic “super PAC,” whose fund-raising has been dwarfed by Republican groups. The new policy was presented to the campaign’s National Finance Committee in a call Monday evening and announced in an e-mail to supporters.

“We’re not going to fight this fight with one hand tied behind our back,” Jim Messina, the manager of Mr. Obama’s re-election campaign, said in an interview. “With so much at stake, we can’t allow for two sets of rules. Democrats can’t be unilaterally disarmed.”

Neither the president, Vice President Joseph R. Biden Jr., nor their wives will attend fund-raising events or solicit donations for the Democratic group. A handful of officials from the administration and the campaign will appear on behalf of Mr. Obama, aides said, but will not directly ask for money.