President and CEO of U.S. automaker General Motors Co. Fritz Henderson resigned Tuesday and his job was taken over on an interim basis by the company's chairman, Ed Whitacre Jr..

At a hastily called press conference in the auto city of Detroit, Whitacre said he would be working out of the company's headquarters on a daily basis until a new president and CEO is named. He took no questions at the press conference.

"We all agreed some changes needed to be made going forward," said Whitacre, the former AT&T CEO who has clashed with Henderson on a number of fronts in recent weeks.

Whitacre was installed by the Treasury Department as the company's chairman after GM's bankruptcy reorganization.

GM's board has had a search ongoing for a new chief financial officer and interviewed many candidates in recent weeks. Those candidates will now be considered for the CEO.

GM made this decision and notified the U.S. Treasury Department which holds a 61-percent majority stake in GM.

"This decision was made by the board of directors alone. The administration was not involved in the decision," the White House said.

Henderson, who was a college pitcher at the University of Michigan, joined GM in 1984 after attending Harvard Business School, and became CEO in April after the Obama administration forced out chairman and CEO Rick Wagoner.

Henderson held a number of positions, including head of its Brazil operations, Latin American unit. In 2002, he became president of GM Asia Pacific.

In 2004, Henderson was named head of GM Europe, followed by a promotion to CFO in June 2006. He had clashed with the board over the decision to sell the company's European unit Opel and Vauxhall. The board rejected management's proposal to sell the unit.

Whitacre, a Texan who was named GM chairman in June after retiring in 2007 as CEO and chairman of AT&T, said in a short statement: "We are united, and committed to the task at hand, and are looking forward to it.”

He assured dealers, suppliers and unions that daily business at GM would be “normal.”

According to the Wall Street Journal's real-time blog on the unfolding events, "In recent weeks it had become increasingly clear that Fritz Henderson's tenure as GM CEO was in jeopardy as publicly and behind the scenes he and board members seemed to be on opposite pages."

The board's decision to keep Europe's Opel operation, even as Henderson had pushed for selling it off, was the most poignant sign that directors and CEO were at odds.

Another area of disagreement may have been what to do with Saab. GM says it will evaluate its options at the end of December, and without a viable buyer "an orderly closure of Saab would be pursued."