Possible Clues:

• Upper House abbr.
• One of 100 on the Hill: Abbr.
• 1 of 100 in D.C.
• Half a breath mint?
• Obama, before he became pres.
• Six-yr. electee
• One may be junior or senior, in D.C.: Abbr.
• VIP on the Hill: abbr.
• Clinton or Obama, once: Abbr.
• Pol whose term lasts six yrs.