WASHINGTON — Despite a pledge not to take money from lobbyists, President Obama has relied on prominent supporters who are active in the lobbying industry to raise millions of dollars for his re-election bid.

At least 15 of Mr. Obama’s “bundlers” — supporters who contribute their own money to his campaign and solicit it from others — are involved in lobbying for Washington consulting shops or private companies. They have raised more than $5 million so far for the campaign.

Because the bundlers are not registered as lobbyists with the Senate, the Obama campaign has managed to avoid running afoul of its self-imposed ban on taking money from lobbyists.

But registered or not, the bundlers are in many ways indistinguishable from people who fit the technical definition of a lobbyist. They glide easily through the corridors of power in Washington, with a number of them hosting Mr. Obama at fund-raisers while also visiting the White House on policy matters and official business.