I've been doing a bit more reading of political science research and am bumping this up a little to 75/25. Partisanship, both positive and negative, is a tough nut to crack, and ultimately I think that should win out.
I also want to point out that I think the betting sites could very well be wrong, since I see their odds come up from time to time when people make their predictions. GJOpen often has a better Brier score than the betting sites do. Back on October 22, 2020, I captured the odds on the various sites. Here were the odds given by GJOpen compared with PredictIt for the upcoming 2020 Presidential election on that date:
1) Biden to win election: PredictIt 0.64, GJOpen 0.83, Result 1.0
2) Biden to win AZ: PredictIt 0.57, GJOpen 0.68, Result 1.0
3) Biden to win FL: PredictIt 0.46, GJOpen 0.65, Result 0.0
4) Biden to win MI: PredictIt 0.69, GJOpen 0.92, Result 1.0
5) Biden to win OH: PredictIt 0.30, GJOpen 0.45, Result 0.0
6) Biden to win PA: PredictIt 0.65, GJOpen 0.85, Result 1.0
7) Biden to win TX: PredictIt 0.27, GJOpen 0.26, Result 0.0
8) Biden it win WI: PredictIt 0.68, GJOpen 0.86, Result 1.0
So as you can see, the GJOpen's Brier on those 8 predictions was 0.1205, which beats PredictIt's Brier of 0.12577. So at least based on that, I wouldn't recommend using betting odds to inform your odds here.