President Bush's top economic adviser is leaving his post, the White House announced Wednesday.

N. Gregory Mankiw (search), the chairman of the president's Council of Economic Advisers, submitted his letter of resignation.

White House press secretary Scott McClellan would not discuss possible replacements. McClellan said Mankiw made it known when he took job he planned to serve for two years and then return to Harvard (search) and that the president appreciates his service. "He has done an outstanding job," McClellan said.

Before coming to the White House, Mankiw had written popular college textbooks on economics that explained complex economic principles in clear and precise language.

He created a stir in last year's election when he said the transfer of U.S. jobs overseas -- sometimes referred to as "outsourcing" (search) -- is sometimes a good thing. Democratic presidential candidate John Kerry and other Democrats seized on the remark to criticize Bush's economic policies and leading Republicans also castigated Mankiw for the comments.

Mankiw has long been expected to leave. Officials have said a leading candidate under consideration to replace him is Ben Bernanke (search), currently serving as one of seven members of the Federal Reserve board. Bernanke has also been mentioned as a top prospect to replace Fed Chairman Alan Greenspan, whose term ends in January 2006.