Voters take to the polls to cast their ballots in Arizona, Maine, Virginia, Nevada, North Dakota and South Carolina today. Residents of these respective states will decide on a series of contests including a special election, a crowded Republican Senate primary and a decision on whether to change a university nickname. Here are the top four things to watch in today's voting contests.

1.) Special Election in Arizona

The race to fill the seat left open by the retirement of former Rep. Gabby Giffords, who stepped down from Congress in January, takes place today in Arizona's 8th congressional district. Ron Barber, Giffords' former district director, and Jesse Kelly, a former marine who also ran against Giffords in 2010, will face off in the Republican-leaning district. Polling shows Barber in the lead but the race is far from certain.

2.) Senate Primaries in Maine

When Republican Senator Olympia Snowe announced her decision to retire in February, the Senate map for Democrats briefly looked very exciting. Maine is considered to be a relatively blue state, and the state boasted a deep bench of potential Democratic contenders. But both parties were thrown for a loop when former Independent Gov. Angus King announced he would be jumping in the race. With many assuming King would ultimately end up caucusing with the Democrats (King has so far refused to commit to either party,) the more-well known Dems in the state opted not to enter the race, while Republicans continued to enter in droves. Six Republicans and four Democrats are on the ballot today, with an interesting three-way race soon to follow.

3.) North Dakota's Nickname Referendum

In North Dakota, turnout is expected to be driven by two ballot measures- a referendum to ban property taxes in the state, and a referendum on whether to discontinue the University of North Dakota's "Fighting Sioux" nickname. The referendum- known as Senate Bill 2370- asks voters to decide whether they would prefer to allow the university to discontinue the nickname or logo, or require the university to use said nickname and logo. The school's mascot has been under fire for some time, and the debate over retirement has been on-going. Supporters of the measure argue that the nickname negatively affects the school's athletics program (in addition, of course, to the argument that the nickname is offensive.) Polling indicates a majority of support for the measure.

If it passed, the nickname would not be changed until January, 2015 at the earliest, and it is not know what the new nickname and logo might be. UND would join a relatively large group of universities who have retired Native American nicknames and mascots over the past several decades including Miami University, Seattle University and the College of William and Mary.

4.) Official start of close key Senate races in Virginia, Nevada and North Dakota.

What do Virginia, Nevada and North Dakota have in common? They're all states with closely-watched, tightly contested Senate races this fall. With Democrats holding onto the narrow majority in the Senate, Republicans are hoping to potentially pick-up seats in Virginia and North Dakota, while Democrats are hoping to pick one up in Nevada.

The candidates in these races are already virtually known (barring any surprise upsets.) In Virginia, Democrat Tim Kaine is running unopposed, and Republican George Allen is the clear front-runner in the GOP field. In Nevada, Rep. Shelley Berkley is expected to officially claim the Democratic nomination, while Senator Dean Heller will, in all likelihood, officially win the Republican nod. And in North Dakota, former Attorney General Heidi Heitkamp is running unopposed for the Democratic nomination and Rep. Rick Berg is considered the likely GOP nominee.