Collins benefited from a tendency among Mainers to split tickets in 2008, when 58 percent backed Barack Obama, and 61 backed her. The same tendency helped her in 2020.

Susan Collins’ ability to win under these rules is affected by her standing in the state, the configuration of the slate of candidates, and a pattern of partisan polarization toward ranked choice in Maine. 

Susan Collins’ purported centrist credentials have relied in part on her stance as an advocate of reproductive rights. That sort of positioning works well in Maine. But, with her vote for Kavanaugh, Collins lost endorsements that could prove detrimental to her reelection.

Maine has a long history of, and appreciation for, independent legislators.