Possible Clues:

• HCH successor
• Drive along the East R
• Subj. of the 2008 biography 'Traitor to His Class'
• Yalta Conference monogram
• Prez with fireside chats
• The F.D.I.C. was created during his presidency
• His DC memorial opened in 1997
• Subj. of a three-volume Arthur Schlesinger history
• Early UN supporter
• Pres. who nominated Hugo Black