DETROIT (Dec. 18, 11:50 a.m. ET) — General Motors has appointed the head of its Brazil operations as the company’s global purchasing czar.

Grace Lieblein, 52, will oversee GM’s $77 billion annual purchasing budget as the company’s vice president of global purchasing and supply chain, GM said in a statement today. She will assume the post immediately, reporting to GM Vice Chairman Steve Girsky.

The position wields enormous power throughout the world’s supply chain, influencing more than 3,000 suppliers that provide parts, components and services to GM’s global operations.

Lieblein succeeds Bob Socia, who in September was reassigned to head GM China. Kim Brycz, who had served as the interim purchasing chief, will keep her post as executive director of GM’s indirect materials, machinery and equipment.

Socia, who became purchasing czar in 2009, won praise from suppliers for improving communication and transparency around GM’s technical needs and production schedules. Under his watch, GM’s standing in industry supplier-relations ratings has risen steadily.

Since April 2011, Lieblein has been president and managing director of GM Brazil. Before that, she was president of GM Mexico.

Since joining GM as a co-op student in 1978, Lieblein has served in a variety of leadership roles in engineering, product development and manufacturing, GM said.

“Grace’s track record is a diverse and very successful one that has prepared her well for this critical role,” Girsky said in a statement.

“Her wealth of experience in product development, manufacturing and general management gives her the insight needed to lead our Global Purchasing and Supply Chain organization and develop mutually beneficial and productive relationships with our suppliers.”