OKLAHOMA CITY -- Walgreen's ( WAG) Chairman and CEO Jeffrey Rein has decided to step down two days after the company abandoned its plans to buy Longs Drug Stores ( LDG). Rein joined Walgreen 26 years ago and helped build the company into the nation's largest drugstore chain. He lasted just two years as CEO and one as chairman of the board. At the age of 56, he is leaving nearly a decade before most people choose to retire at the company. Walgreen gave no reason for Rein's sudden departure when announcing the news on Friday. Instead, newly appointed Chairman Alan McNally simply thanked Rein for his "outstanding contributions" and expressed "respect" for his decision to retire. McNally will double as interim CEO until a permanent leader can be found. Two years ago, Rein looked like Walgreen's answer. In tapping him as CEO, Walgreen said the move was part of its official "long-range leadership succession" plan. ""He's had proven success building our people and our business in the Southwest, and he's done the same at the national level through 10 very productive years in several key corporate positions," Walgreen said of Rein at the time. "There isn't a segment of our business in which Jeff hasn't been intimately involved, and he's a key player in our strategy and our operations. "He's providing strong, energizing leadership as president and will continue to do so as CEO." Last year, Walgreen went a step further when it named Rein chairman of the board and called him the ideal leader for the company.