As the battle for the Senate heats up with post-Kavanaugh polls forecasting a Republican resurgence, The Circus travels the country charting the shifting dynamics in three of the closest races - each considered a must-win if Democrats hope to gain the majority. In Arizona, it's neck and neck between Kyrsten Sinema and Martha McSally; in Nevada, Jacky Rosen digs deep to take on incumbent Dean Heller; plus, a sit-down with North Dakota's Heidi Heitkamp, who's fighting for her political life in the wake of a campaign ad controversy.