A state-by-state look at what is topping the ticket in Tuesday's election:
ALABAMA — Republican Sen. Jeff Sessions has no opposition for a fourth term. Republican Gov. Robert Bentley is favored for re-election to a second term. Republican Gary Palmer is poised to win the state's one open House seat.
ALASKA — Sen. Mark Begich, a Democrat, tries to fend off Dan Sullivan, an ex-State Department appointee in George W. Bush's administration, in a race that could tip the balance of power in the Senate. Dogged by an Alaska National Guard scandal, incumbent Republican Gov. Sean Parnell faces an uphill battle against a combined independent-Democratic ticket.
ARIZONA — Former ice cream chain CEO Doug Ducey is in a difficult-to-forecast governor's race against Democrat Fred DuVal. Republicans hope to gain two House seats in swing districts.
ARKANSAS — Two-term Democratic U.S. Sen. Mark Pryor fighting for third term against Republican rival and U.S. Rep. Tom Cotton in heated and expensive race. Republican Asa Hutchinson running against Democrat and fellow ex-congressman Mike Ross in open governor's race that national GOP figures have targeted after eight years under a popular Democratic incumbent.
CALIFORNIA — Democrat Jerry Brown is pitching a water bond and a rainy day fund as he seeks re-election to an unprecedented fourth term as governor over former U.S. Treasury official Neel Kashkari. Special interest groups have also poured millions of dollars into three toss-up congressional races.
COLORADO — Democratic Sen. Mark Udall and Republican Rep. Cory Gardner are in a fierce race, as are Democratic Gov. John Hickenlooper and Republican Bob Beauprez. Democrats are targeting one House Republican, Mike Coffman.