Historical clue formulations

• Unaffiliated voters: Abbr. — 2019-02-20
• Unaffiliated voters: Abbr. — 2019-01-09
• Hill minority: Abbr. — 2013-08-10
• Neither Dems. nor Reps. — 2012-11-27
• Middle-of-the-roaders: Abbr. — 2006-02-11
• They're unaffiliated: Abbr. — 2004-11-12
• Some candidates: Abbr. — 2000-11-12
• They're often responsible for upsets: Abbr. — 2000-05-06
• Some voters: Abbr. — 1995-07-08