PHILADELPHIA -- Michael D. Eisner was toppled from his position as chairman of Walt Disney Co. Wednesday night when the company's board responded to an extraordinary shareholder protest by naming former Maine Sen. George Mitchell to the position.

Eisner, who ran the company single-handedly for the last 20 years, will continue as chief executive officer but will report to Mitchell and the board.

The action came at the end of a frenetic day in which holders of 43 percent of Walt Disney Co. withheld their votes at the company's annual meeting, opposing Eisner's re-election as chairman.

Never before in American corporate history has a successful company been hit with such a groundswell of shareholder dissatisfaction.

While the Disney directors voted unanimously to make Mitchell chairman, they voiced their continuing approval of Eisner's management and the company's strategy. They described Mitchell's newly-created position as "non-executive."

The board's decision to keep Eisner at the helm as chief executive is not likely to satisfy vociferous critics who have pursued an aggressive campaign to have him fired.

Two former directors of the company, Roy E. Disney, a nephew of founder Walt Disney and his ally, Stanley P. Gold, have argued that Eisner's departure is essential.

The shareholders' vote "has sent a clear and very undeniable message that Michael Eisner must go. ... We think the shareholders have spoken," Gold said late Wednesday.

Mitchell, the new chairman, is already a suspect figure in the eyes of Roy Disney and Gold, who view him as too close to Eisner.

Yeterday, shareholders acting on the suggestion of Roy Disney and Gold, withheld more than 20 percent of their votes from Mitchell and two other board members considered friendly to Eisner: Judith Estrin and John Bryson.

"This is a referendum on real governance in corporate America," Gold said amid a whir of flashbulbs about an hour after the meeting ended.

T. Rowe Price Associates Inc., a Baltimore-based mutual fund company, refused to vote its 19.3 million Disney shares as a protest against management. It was one of a dozen major institutional investors that decided to withhold support from Eisner.

"Our view is that there have been a number of recurring issues over the years involving the performance of the company, involving corporate governance is sues, involving executive turnover questions that basically call into question much of what the company has been stating in terms of its performance," Brian C. Rogers, the company's chief investment officer and head of the T. Rowe Price Equity Income Fund, said last week.

A Price spokesman declined further comment Wednesday, saying the vote spoke for itself.

In a statement released after its move to name Mitchell chairman, the board said: "We are aware that some voted for an immediate change in management and in the board. Howver ... we believe the action we have taken today is in the best long- term interest of the shareholders of the company."

"Our belief in the company's strategy, financial results over the last several quarters, and the level of earnings and improved returns we expect going forward make us confident that results will validate our judgment on the quality of our management team," the board statement said.

After the earlier shareholders' vote, Comcast Corp., which last month proposed a $66 billion takeover of Disney, urged the company to reconsider its offer.

"Today's unprecedented with hold vote by Disney's shareholders sends a powerful message that Disney's board and management need to focus more on shareholder interest," said Comcast spokeswoman D'Arcy Rudnay.

"Consistent with this focus, Disney's independent directors should immediately meet with Comcast so we can directly present our full and generous offer and the benefits of the merger."