CHICAGO – In the cluttered office where he’s met with some of the nation’s top politicians and preachers, penned rousing speeches and planned civil rights marches, the Rev. Jesse Jackson speaks so softly – and with so little enunciation – that one strains at times to hear him.

At 71, he still keeps a hectic schedule and speaks extemporaneously on issues from voting rights to prisoners in Gambia. But the head of one of America’s most prominent families struggles when addressing one thing: the son and political heir who abandoned his congressional seat last week because of mental health problems and two federal investigations.

Sitting in his office – among photographs of mentor Martin Luther King – the elder Jackson’s body tenses, he sighs and his eyes drift off.