- West Virginia - Incumbent: Democrat Joe Manchin
- Montana - Incumbent: Democrat Jon Tester
- Ohio - Incumbent: Democrat Sherrod Brown
- Arizona - Incumbent: Independent Kyrsten Sinema
- Nevada - Incumbent: Democrat Jacky Rosen
- Wisconsin - Incumbent: Democrat Tammy Baldwin
- Pennsylvania - Incumbent: Democrat Bob Casey
- Michigan - Incumbent: Democrat Debbie Stabenow (retiring)
- Texas - Incumbent: Republican Ted Cruz
- Florida - Incumbent: Republican Rick Scott
People in the “minority” party districts get complacent that their district will be safe so there’s lower turnout (Harris County in Tx, 3rd largest county in the country, heavily Democratic, had under 50% turnout in the 2020 elections). People in “majority” party districts feel like there’s no hope they’ll be represented, so they give up and don’t vote.