As hope virtually vanished of finding Mr John F. Kennedy jnr, his wife, Carolyn, and her sister, Lauren Bessette, alive after the disappearance of their small aircraft, President Clinton offered "the prayers of all Americans" to their families.
The single-engined Piper Saratoga owned by the son of the late President Kennedy was bringing the group to the wedding of Ms Rory Kennedy at Hyannisport. The wedding was postponed as soon as the aircraft was reported missing early on Saturday.
The President has been closely following the massive recovery efforts since the plane, piloted by Mr Kennedy, went down off Martha's Vineyard island on Friday night. Last night, search efforts were concentrating on a small area after a radar detection ship, the Rude, detected a signal.
Numerous aviation experts have been expressing surprise that such an inexperienced pilot as Mr Kennedy - he only had a basic licence for 15 months - should have made the 180-mile trip from New Jersey to the island in the thick haze and darkening conditions of Friday evening. Contrary to early reports he was not accompanied by a flight instructor.
Mr Jim Hall, the chairman of the National Transportation Safety Board, which has joined the operation to locate the missing aircraft, warned that it was possible it might never be found.
President Clinton, after arriving at the White House from Camp David, paid tribute to the role of the Kennedy family in American public life. "For more than 40 years the Kennedy family has inspired Americans to public service, strengthened their faith in the future and moved our nation forward. Through it all they have suffered much and given more," the president said.
Some more debris believed to be from the downed aircraft was found along beaches on Martha's Vineyard yesterday. The objects included foam insulation and part of a headrest. On Saturday, searchers found a bag belonging to Ms Lauren Bessette. A prescription box of Mrs Kennedy and another headrest were also found as well as a strut from the aircraft.
These findings enabled the search for the aircraft to be more concentrated than previously. The search planes, ships and helicopters then focused on a 550-square mile area just south-west of Martha's Vineyard.
As the reality of the latest tragedy to hit the Kennedy family began to sink in across America, there were reports of widespread prayers and grieving in churches. At the Kennedy family compound in Hyannisport, relatives of the missing Kennedys and guests who had been invited for the wedding of Ms Rory Kennedy, youngest daughter of the assassinated Robert Kennedy, attended a Mass, while John jnr's sister, Ms Caroline Kennedy Schlossberg, awaited news from Long Island.
At a press conference early this morning at Otis Airfield, Massachusetts, the US Coastguard confirmed that its operation to locate Mr Kennedy's plane had shifted from one of search and rescue to search and recovery. The Coastguard spokesman said a number of target areas had been identified during its search and divers would be sent to investigate these sites at first light today.