Possible Clues:

• W.'s political affiliation
• Its convention was in St. Paul
• Org. with a Boehner for frustrating Obama
• Org. with an elephant in its logo
• Dems' foe
• Increasingly archaic name for the Republican Party
• Whigs' successor, briefly
• Red letters, briefly?
• Lincoln was its first successful standard-bearer, for short
• Org. with an elephant logo