** ADVANCE FOR SUNDAY, NOV. AND THEREAFTER -- FILE ** In this March 24, 1988 file photo, Sen. Joseph Biden, D-Del., wearing a University of Delaware baseball cap, leaves Walter Reed Army Hospital in Washington accompanied by his son Hunter Biden. Biden had been in the hospital for 11 days so that surgeons could implant a small umbrella-like filter in a vein to prevent blood clots from reaching his lungs. (AP Photo/Adele Starr, File)