Tonight's cheat sheet: The Big 3 races to watch

Two of the three races below will likely determine Senate control, while the third gives a major preview of the GOP's political future.

1. Georgia is where Republicans lost control of the Senate two years ago. The state requires a 50%+ majority to win, so we could have a runoff that delays a balance of power shift until Dec. 6. Tonight features Herschel Walker (R) vs. Raphael Warnock (D).
2. Pennsylvania is where Joe Biden, Donald Trump and Barack Obama all campaigned last weekend. It's an open Senate seat that's been GOP-held, potentially offsetting Democratic losses in other states. Tonight is John Fetterman (D) vs. Mehmet Oz (R).
3. Arizona matters because GOP gubernatorial nominee Kari Lake — a former TV news celebrity — has been described as a potential Trump heir, but the state elected Joe Biden in 2020. Lake is running against Democratic nominee Katie Hobbs.