(AP) -- Deputy Secretary of State Robert Zoellick Monday announced his resignation to join investment house Goldman Sachs, after focusing on China and Sudan in the No. 2 job at the department.

Zoellick, a former U.S. trade representative before moving to the State Department in February 2005, had been tipped as a candidate for treasury secretary but he was passed over for the job which went to Goldman Sachs chairman Henry "Hank" Paulson.

Last month, Zoellick played a pivotal role in getting the main rebel groups in Sudan's western Darfur region to sign a peace agreement after talks had dragged on for years. He had made several trips to the region.

Darfur activists voiced concern that his successor might not devote as much time to the issue and they urged the Bush administration to appoint a special envoy for the region. "More than anyone else he (Zoellick) has moved this forward and come up with tangible results. It is a matter of concern when one of the administration's point people decides to leave," said Alex Meixner, policy director for the Save Darfur Coalition, an alliance of groups that raises public awareness about Darfur.

A candidate to succeed Zoellick has not yet been identified but Rice's top aid official, Randall Tobias, could be among those on a short list, said one official.

Copyright 2022 NPR. To see more, visit https://www.npr.org.