Republican presidential hopeful Rudy Giuliani has stepped down as head of his consulting firm, Giuliani Partners, after months of refusing to disclose the firm's clients or the role he played.

Giuliani has been replaced as chairman by Peter Powers, a longtime friend and former aide, Giuliani Partners spokeswoman Sunny Mindel said Tuesday. The change was reported by The Wall Street Journal earlier Tuesday, and Mindel noted news stories over recent months saying Giuliani was handing control to Powers.

The firm, started by the former New York mayor when he left City Hall, earned Giuliani around $4 million last year. The spokeswoman said he would retain his equity stake in the company.

While insisting the firm's client list was confidential, Giuliani has noted the media have named a number of his clients.

Published reports have identified one client as the Persian Gulf country of Qatar, which was accused of sheltering suspected Sept. 11 mastermind Khalid Sheikh Mohammed, although today it is a U.S. ally.

Also identified as Giuliani clients are airlines, energy companies and communications businesses; one client, Purdue Pharma L.P., makes the controversial painkiller OxyContin. His law firm, Houston-based Bracewell & Giuliani, has represented an American subsidiary of an oil company controlled by Hugo Chavez, the Venezuelan president.

Giuliani aides said he has not been involved in day-to-day operations of the firm since last spring. Yet he never formally announced he had relinquished his titles, despite being asked repeatedly about it. The firm's Web site listed him as chairman as recently as last month.

He has used the office in Times Square to conduct campaign activity, such as giving interviews; aides said Giuliani's campaign pays for office and conference space for meetings.

Asked in a Nov. 5 interview with The Associated Press to outline his role in the firm or list its clients, Giuliani laughed, then grew agitated:

"Everything I did at Giuliani Partners was totally legal, totally ethical," he said. "There's nothing for me to explain about. We acted honorably, decently."

He added: "There are some things that a law firm and security firm do that are confidential. You can't release it because the client asks for confidentiality. We do sensitive work. So maybe there are some exceptions like that."

Giuliani said it's unfair to ask for details about his consulting firm as well as his law firm, Bracewell & Giuliani.

"What's the standard? Giuliani Partners and Bracewell Giuliani are firms. Nobody has ever accused them of doing anything wrong. So all of the sudden, you are going to start jumping to conclusions about them when there are absolutely no suggestion they have done anything wrong?"

Giuliani had income of $4.1 million from his share in the consulting business and $1.2 million from Bracewell between January 2006 and February 2007, he reported in financial disclosure forms filed in May.

Critics accuse him of hiding his business dealings because he won't release a client list or describe his work at the firm.

"Given that he still has a financial stake in Giuliani Partners and it's managed by his childhood friend, Rudy is not going to get away with covering up his ties to shady clients like the government of Qatar, the pharmaceutical industry, and Hugo Chavez," Democratic National Committee spokesman Dag Vega said.