Indeed, Mr. Rubin is expected to step down from the bank altogether after board settles on a new leadership structure, this person said.  Mr. Rubin’s standing at Citigroup has long been contentious. In better times, his role as a board member and chairman of the bank’s executive committee was often referred to as the “best job in the world.”  He has collected more than $150 million in cash and stock over eight years to serve as the bank’s elder statesman, meeting with important clients and building relationships with government and business leaders around the world, though his contract states that he is to have no daily operational responsibilities.  His other role has been to serve as Mr. Prince’s sounding board and biggest supporter — and to help broadly shape the bank’s strategy. The bank’s performance, however, has come under criticism, with Citigroup’s stock remaining essentially flat from the time Mr. Prince took over in October 2003 until recently. Since a sharp downturn in the housing and credit markets began in August, the stock has dropped nearly 20 percent.  Mr. Bischoff, 66, was born and raised primarily in Germany. His family moved to South Africa when he was a teenager, and he graduated from college there with a degree in commerce in 1961.  He began his career in banking at Chase Manhattan the following year, but spent most of it rising through the ranks of Schroders, the British investment bank. He became group chief executive of Schroders in 1984 and served as chairman from 1995 to 2000, when the bank was acquired by Citigroup.  He was knighted the same year, testimony to the deep ties he had developed with a wide range of powerful clients and British institutions like the Royal Opera House at Covent Garden, where he was a trustee.  Mr. Bischoff's reputation in London also put him on the radar of American companies with a growing presence overseas, leading to invitations to join the boards of McGraw Hill in 1999 and Eli Lilly in 2000.  Last month, Citigroup’s third-quarter earnings fell 57 percent after it took the write-off and virtually all of its businesses took heavy losses. And the problems continue to mount. At a meeting today, Citigroup’s board is expected to be briefed on the possibility of even greater losses.  Mr. Rubin, however, has emerged largely unscathed. Executives say he offers advice but does not insist that people act on it. And he has long been adamant that he has no responsibility for the decisions made by Mr. Prince and Citigroup’s other leaders.  That contrast has allowed Mr. Rubin to float above the fray, even as he has helped guide the bank during Mr. Prince’s tumultuous tenure. Now, some suggest that the turmoil has tarnished Mr. Rubin’s credentials.  “You have to ask yourself why he would be temporary chairman if all these problems happened under his auspices,” said Douglas A. Kass, a hedge fund investor at Seabreeze Partners Management in Palm Beach, Fla. “Four or six months ago, I would have said it would be a great remedy to replace Prince with Rubin. Now, I am not so certain.”  Of course, the board may already be pursuing other options for the job of acting chief executive. Vikram S. Pandit, who took over Citigroup’s investment banking operation in early October, just six months after joining the bank, is one contender.  Mr. Pandit’s love of complex, technical problems and his years of experience in dealing with clients, risk and the more arcane aspects of what makes investment banks run at Morgan Stanley has piqued his curiosity, according to people close to him.  But as of late morning Saturday, no one on the board had reached out to him, these people say. Other potential candidates include Robert Druskin, the company’s chief operating officer; and Gary L. Crittenden, its recently named finance chief. They might join Mr. Rubin or other high-ranking bank executives as part of a larger committee overseeing the bank.  Landon Thomas Jr. and Gretchen Morgenson contributed reporting.
The board of Citigroup accepted the resignation of Charles O. Prince III today and appointed Robert E. Rubin, the former Treasury secretary, as its chairman.