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.
CONNECTICUT — Democratic Gov. Dannel P. Malloy is in a tight race against Tom Foley, the Republican businessman he narrowly defeated in 2010, as Democratic incumbents in all five U.S. House districts look to hold off GOP challengers.
DELAWARE — Democratic U.S. Sen. Chris Coons seeks a full six-year term after defeating tea party activist Christine O'Donnell in a 2010 special election for Joe Biden's former seat. Republicans try to keep the lone statewide office they hold and to gain another as well.
DISTRICT OF COLUMBIA — Democrat Muriel Bowser is favored to continue her party's winning streak in the race for mayor of the heavily Democratic nation's capital, despite a stronger-than-usual general election challenge from independent David Catania.
FLORIDA — Republican Gov. Rick Scott is in a tight battle with Democrat Charlie Crist, who was a Republican when he was elected to the office in 2006. Amendment 2, which would legalize medical marijuana, needs 60 percent approval to pass, and it is going to be close. Only two of the 27 congressional races are expected to be competitive - one is held by a Republican and the other a Democrat.
GEORGIA — Republican David Perdue and Democrat Michelle Nunn are competing for an open U.S. Senate seat, while Gov. Nathan Deal, a Republican, faces a challenge from Democrat Jason Carter, a state senator and the grandson of former President Jimmy Carter.
HAWAII — Sen. Brian Schatz appears to be in a safe seat for Democrats in President Barack Obama's native state; fresh off a stunning upset in the Democratic primary, state Sen. David Ige is favored to replace unpopular Gov. Neil Abercrombie but faces a tough fight from Republican James "Duke" Aiona.
IDAHO — Gov. C.L. "Butch" Otter is favored to win a rare third term but faces stiff competition from Democratic businessman A.J. Balukoff and Libertarian attorney John Bujak. Congressional GOP incumbents Sen. Jim Risch and Reps. Mike Simpson and Raul Labrador are expected to sail to victory.
ILLINOIS — Democratic Gov. Pat Quinn is facing a tough challenge from wealthy GOP businessman and first-time candidate Bruce Rauner for control of Obama's home state.
INDIANA — GOP Rep. Jackie Walorski is favored to hold the seat Democrat Joe Donnelly gave up in 2012 for a successful U.S. Senate bid.
IOWA — The race for U.S Senate remains tight between Republican Joni Ernst and Democrat Bruce Braley while Republican Terry Branstad is expected to cruise to easy re-election as governor.
KANSAS — In a race crucial to GOP hopes for Senate control, Republican U.S. Sen. Pat Roberts is in a too-close-to-call match with independent Greg Orman. For governor, tax-cutting Republican incumbent Sam Brownback gets a stiff challenge from Democrat Paul Davis.
KENTUCKY— Democrat Alison Lundergan Grimes says the election is a referendum on Republican Sen. Mitch McConnell, the minority leader. McConnell says the election is a referendum on Obama. Voters will decide who is right.
LOUISIANA — The only Democratic statewide elected official, Sen. Mary Landrieu is threatened in her bid for a fourth term by national Republican efforts to oust her and retake control of the Senate. This race is expected to go to a Dec. 6 runoff between Landrieu and her main GOP challenger, Rep. Bill Cassidy.
MAINE — Democrat Mike Michaud would be the nation's first openly gay governor if he can unseat Republican Gov. Paul LePage. GOP Sen. Susan Collins is expected to cruise to a fourth term.
MARYLAND — Democratic Lt. Gov. Anthony Brown and Republican Larry Hogan are in a competitive governor's race in a state where registered Democrats outnumber Republicans 2-1. Congressional incumbents are not facing any stiff challenges.
MASSACHUSETTS — Democrat Martha Coakley, battling to become the first woman elected governor, is locked in a tight race with Republican Charlie Baker, who is trying to return the office to GOP hands for the first time since Mitt Romney left in 2007.
MICHIGAN — GOP Gov. Rick Snyder is in a tight race for re-election with Democrat Mark Schauer. Democratic U.S. Rep. Gary Peters is favored to win the U.S. Senate seat being vacated by mentor Carl Levin.
MINNESOTA — U.S. Sen. Al Franken and Gov. Mark Dayton are favored to keep top statewide seats in Democratic hands, but the party's lock on state government is tenuous. The GOP is seen as likely to take the state House.
MISSISSIPPI — Six-term Sen. Thad Cochran won a tough Republican primary and has ignored two challengers, Democratic former U.S. Rep. Travis Childers and the Reform Party's Shawn O'Hara; one Democrat and three Republicans in the House are safe.
MISSOURI — Only statewide office on the ballot is auditor, with the incumbent Republican facing two third-party candidates. Four ballot measures include one that could end teacher tenure, while local legislative races could give GOP veto-proof majorities in the Capitol.
MONTANA — GOP Rep. Steve Daines is expected to win Sen. John Walsh's seat after Walsh dropped out in August over plagiarism revelations.
NEBRASKA — Republican Ben Sasse should easily win an open Senate seat in conservative Nebraska, but Democrat Brad Ashford and incumbent Republican Rep. Lee Terry are in a close race for an Omaha-based House seat.
NEVADA — GOP Gov. Brian Sandoval eyes an easy lopsided victory amid a Republican early voting wave that has nervous Democrats scrambling to catch up.
NEW HAMPSHIRE — Former Massachusetts Sen. Scott Brown is hoping to oust incumbent Democrat Jeanne Shaheen to secure his comeback to Washington from a second state.
NEW JERSEY — Republicans are trying to keep the 3rd Congressional seat in an open race between self-funded Republican Tom MacArthur and Democrat Aimee Belgard, whose campaign has been supplemented by independent spending from national groups.
NEW MEXICO — Republican Gov. Susana Martinez is leading Attorney General Gary King in pursuit of second term. Republicans are looking to reclaim a legislative chamber for the first time since the Eisenhower administration.
NEW YORK — Democratic Gov. Andrew Cuomo remains a heavy favorite in polls, while a series of close races will determine whether Republicans keep majority control of the state Senate.
NORTH CAROLINA — Democratic incumbent Sen. Kay Hagan and GOP challenger Thom Tillis are battling down to the wire for the Senate seat in a key swing state; polls indicate a virtual dead heat.
NORTH DAKOTA — Republican U.S. Rep. Kevin Cramer appears headed to re-election, while Agriculture Commissioner Doug Goehring, one of three people who sits on a panel that regulates oil, is in a tight race with Democratic challenger Ryan Taylor.
OHIO — GOP Gov. John Kasich is headed to a big re-election victory in what could shape up as a good day for Republicans across the state.
OKLAHOMA — Both of Oklahoma's U.S. Senate seats are on the ballot, and Republicans are heavy favorites to retain both. Republican Gov. Mary Fallin is expected to return for another four years.
OREGON — Sen. Jeff Merkley and Gov. John Kitzhaber, both Democrats, are likely to be re-elected, but a ballot measure to legalize marijuana could go either way.
PENNSYLVANIA — Democrat Tom Wolf appears poised to send Republican Gov. Tom Corbett to a historic defeat, making him the first incumbent to lose in the four decades since Pennsylvania's chief executive was allowed to run again.
RHODE ISLAND — Democrat Gina Raimondo and Republican Allan Fung are in a close race for governor, while twice-convicted felon Buddy Cianci is attempting a comeback as Providence mayor.
SOUTH CAROLINA — Republican Nikki Haley is expected to easily win re-election for governor, increasing her national visibility in the Republican Party. Republicans Lindsey Graham and Tim Scott also are on track to retain their U.S. Senate seats.
SOUTH DAKOTA — After the U.S. Senate race tightened up due to an infusion of outside advertising money and nagging questions about his leadership as governor, Republican Mike Rounds has regained his status as front-runner over Democrat Rick Weiland and independents Larry Pressler and Gordon Howie.
TENNESSEE — Republican Lamar Alexander is favored for a third term in the Senate, but spending hold off long-shot Democrat Gordon Ball. Republican Gov. Bill Haslam is cruising to a second term against Charles V. Brown, a Democrat who has mounted no organized campaign.
TEXAS — Republican Greg Abbott is heavily favored over Democrat Wendy Davis to become Texas' first new governor since 2000. Democrats are unlikely to end a 20-year losing streak in statewide races.
UTAH — Republican Mia Love could become the first black female Republican in Congress. Interim Republican Attorney General Sean Reyes is likely to earn two more years in office.
VERMONT — Democratic Gov. Peter Shumlin is expected to be the top vote-getter in the election, but the race will be decided by the Legislature if his vote total doesn't reach 50 percent.
VIRGINIA — Sen. Mark Warner has maintained a consistent lead over GOP challenger Ed Gillespie in polls. Dave Brat, who defeated then-U.S. House Majority Leader Eric Cantor in June primary, aims to win general election.
WASHINGTON — Voters decide whether to increase the number of background checks on gun sales and transfers conducted in Washington state.
WEST VIRGINIA — Republican Shelley Moore Capito is favored to defeat Democrat Natalie Tennant for retiring Sen. Jay Rockefeller's open seat, with two congressional contests and control of the Democratic state House of Delegates still up in the air.
WISCONSIN — Republican Gov. Scott Walker is in a tight re-election bid against political newcomer Democrat Mary Burke, two years after his recall victory and with a potential 2016 presidential bid at stake.
WYOMING — Republican Sen. Mike Enzi and Rep. Cynthia Lummis are cruising to fourth terms. GOP Gov. Matt Mead is poised for a second term.