Historical clue formulations

• "I ___ been a contender ..." — 2026-03-09
• Might have, informally — 2022-02-15
• Had the opportunity to, casually — 2021-12-26
• Might have, informally — 2015-06-14
• Part of an "if only ..." lament — 2014-06-04
• "___ Been the One" (2006 Rihanna song) — 2010-04-16