Mark Lippert, a key aide to U.S. President Barack Obama and chief of staff to Defense Secretary Chuck Hagel, is a strong candidate to succeed outgoing U.S. Ambassador to Seoul Sung Kim.
Kim is set to become a deputy assistant secretary of state for East Asia and Pacific affairs.
Sources in Washington on Monday said Kim may be summoned back to the U.S. before his term ends in August of this year, because the current deputy assistant secretary James Zumwalt is likely to be appointed ambassador to Vietnam.
Lippert (41) is in the running because Seoul wants an envoy with direct access to the White House, according to sources.
He started serving Obama as chief assistant for foreign affairs and national security when he was a senator in 2005. After Obama won the 2008 presidential election, Lippert headed the White House National Security Council.
One diplomatic source in Washington said Lippert is being considered because Seoul wants someone of equivalent stature to the new Ambassador to Japan Caroline Kennedy, the daughter of former U.S. President John F. Kennedy.