"November 05, 2008 8:30 AM ABC News has learned that President-elect Obama has offered the White House chief of staff job to Rep. Rahm Emanuel, D-Ill. Emanuel, a knowledgeable source tells ABC News, has not yet given his answer. The sharp-tongued, sharp-elbowed, keenly intelligent veteran of the Clinton White House is said to have ambitions to some day be Speaker of the House. But he also has a keen sense of "duty." Today on "Good Morning America" ABC's George Stephanopoulos reported Obama likes the fact that Emanuel "knows policy, knows politics, knows Capitol Hill" and has told associates that Emanuel would "have his back." Seneca