Unfortunately, there is reason to suspect that Trump supporters may have been less likely to respond to telephone polls in 2020 (Cohn, 2020; Fannon, 2020; also see Gelman et al., 2016; Levitz, 2020; Matthews, 2020; Stanton, 2020). If it is true that Trump supporters were less willing to participate in polls relative to Biden supporters, this would overestimate Biden’s support from the polls as differential nonresponse in this scenario would be associated with candidate preference.
Scott A. Adams