Possible Clues:

• Longtime Mass. senator's monogram
• Longtime 11-Down from Mass
• Monogram of 'The Lion of the Senate'
• Mass. senator's monogram, 1962-2009
• Teddy's monogram
• JFK's kid brother
• Sen. from Mass.
• New Eng. Senate monogram since 1962
• Mass. senator's monogram
• Sen. from 1962