washington retire neurosurgeon ben carson former 2016 republican presidential candidate adviser president-elect donald trump opt accept cabinet position trump administration spokesman say tuesday carson popular writer speaker conservative circle close adviser trump vice chairman trump transition team mention possible secretary health human service education carson business manager armstrong williams say carson make clear experience run federal bureaucracy dr carson feel like best way serve president-elect williams tell reuters say carson would remain close adviser trump friend life prepare cabinet secretary williams say republican ben carson opt job trump cabinet