Citigroup Inc investors withheld more than 20 percent of their votes for the reelection of four directors, after critics said the board's lack of oversight contributed to a series of government bailouts and $37.5 billion of losses over 15 months.

According to a regulatory filing, C. Michael Armstrong, the former AT&T Corp chief executive and a former chair of the bank's audit committee, got just 70 percent of votes in his favor at Citigroup's annual meeting last month.

John Deutch, his successor on the audit committee and a Massachusetts Institute of Technology professor, got 72 percent. Two other directors, Alcoa Inc Chairman Alain Belda and Xerox Corp chief executive Anne Mulcahy each got 77 percent of the vote in their favor.

Chief Executive Vikram Pandit won 91 percent support, while Chairman Richard Parsons, the former chief executive of Time Warner Inc , got 86 percent, the filing shows.

Citigroup's board has 14 members, following the replacement of five directors over the past year and installation of four new directors. The departing directors include former U.S. Treasury Secretary Robert Rubin and Sir Win Bischoff, who preceded Parsons as chairman.

The government is expected to soon become Citigroup's largest shareholder, with a potential 34 percent stake, when the New York-based bank completes a preferred stock conversion as soon as this month.

(Reporting by Jonathan Stempel, editing by Gerald E. McCormick)