The Overton Window shift in the US is mostly due to persistent low primary attendance.
Congressional primaries have seen <15% attendance for the last 40 years. Retirees never miss a vote, and have very different needs than the working class. They’re the ones who have been packing our ballots with centrists and conservatives.
We should be voting twice every two years, not once every four, for federal elections alone. Sign up for mailers if you forget. Research the candidates on the ballot, rather than relying on advertising to coerce you into doing your civic duty.
A lack of challengers is exceedingly rare. I was just discussing Fetterman’s election in another thread, where someone was saying he was better than Dr. Oz, but both options sucked. He also had three challengers in a primary that only saw 8.5% attendance.
https://www.cnn.com/election/2022/results/pennsylvania/democratic-primaries/senate