Hard-charging White House Chief of Staff Rahm Emanuel is leaving the Obama administration to run for mayor of his native Chicago.

When Chicago Mayor Richard Daley, who led the city since 1989, announced he would not run for reelection weeks ago, speculation ran wild that Emanuel would jump at the opportunity to lead the nation's third largest city.

Emanuel, a former congressman with a reputation as an uncompromising taskmaster, is the most recognizable name in a field that could also include a few members of Congress and a former U.S. senator.

Emanuel's prickly personality wouldn't seem to be cut out for elected office where kissing babies, backslapping and handshakes can translate to votes. But no one has ever mistaken Daley, who can be a bit blunt himself, with the typical profile of the warm, fuzzy politician.

Competition for the Chicago mayoralty could be fierce and at least two members of the Congressional Black Caucus are said to be seriously considering a run.

U.S. Rep. Jesse Jackson Jr., son of civil rights activist Jesse Jackson, and U.S. Rep.Danny Davis are popular in the city and could prove tough to beat.

Other challengers could include Cook County Sheriff Tom Dart, U.S. Rep. Luis Gutierrez, former U.S. Sen. Carol Moseley Braun and Chicago Transit Authority chairman Terry Peterson.

Candidates need to collect 12,500 signatures to earn a spot on the February ballot.

For President Barack Obama, the Emanuel departure comes as no huge surprise. It is common for a president to shake-up his close circle of advisors for the second half of his administration to inject new life and ideas into the White House flow.

But it still could prove a big loss.

Emanuel combined the energy and intensity of a newcomer with the Capitol Hill connections and relationships of a longtime Washington insider.

The man expected to replace Emanuel in the interim is senior advisor Peter Rouse, who projects a fairly calm demeanor. After two years with Emanuel, that may take some getting used to around the West Wing.