WASHINGTON - US Congressman Rahm Emanuel, a member of the Democratic leadership in the House of Representatives, has been offered the job to head President-elect Barack Obama's staff, a key post, according to media reports. They said that the job was offered to Emanuel on Wednesday, just hours after Obama was elected, and Emanuel was expected to quickly accept the post of White House chief of staff as Obama set about the task of building an administration in times of crisis as Americans and the world absorbed his history-shattering achievement as the first black leader ascending to the presidency. Obama faced the daunting challenges of two wars and the gravest economic crisis to afflict the country since the Great Depression. Emanuel previously served as a top adviser to former President Bill Clinton.