Possible Clues:

• Song with single note occupying leaders in Oval Office
• Caruso standard
• Song for which Pavarotti won a 1980 Grammy
• Tune for The Three Tenors
• Basis of Tony Martin's 'There's No Tomorrow'
• Song that provided the melody for Elvis's "It's Now or Never"
• Basis for Elvis' ''It's Now or Never''
• Neapolitan song
• Song from endlessly grave one in spectacles
• Common Italian encore