Voters in Maine, Nevada, South Carolina, and North Dakota head to the polls on June 9.

In Maine, the biggest event of the night will be the primary to lock down the Democratic Senate nominee, expected to be progressive candidate Graham Platner. The 2026 Senate race has been characterized as the political fight of Sen. Susan Collins’s life by many observers, though she faces no challenges for the Republican nomination.

In Nevada, a key battleground, voters will make their pick for nominees for governor and the U.S. House of Representatives.

Meanwhile, voters in South Carolina will cast their ballots in the state’s gubernatorial primary, with several high-profile lawmakers competing for the executive nomination. They’ll also make their pick for their U.S. Senate nominees, as Sen. Lindsey Graham seeks a fifth term in the upper chamber.

In North Dakota, voters will cast ballots for the state’s single congressional district. In the deep red statewide district, incumbent Rep. Julie Fedorchak faces a primary challenger. The winner of the primary is all but guaranteed to win the November general election.

Here’s what to know.

Maine

Residents in the Pine Tree State will cast their vote for Senate, governor, and the House.

The Senate race has attracted the most attention, with Democratic candidate Platner, an oysterman by trade, facing several controversies during his campaign.

Specifically, The New York Times has run various stories against Platner relying heavily on claims made by Lyndsey Fifield, a Republican political operative who previously dated Platner.

Fifield claimed that on one occasion while they were dating between 2013 and 2015, Platner twisted her arm. The New York Times stated in the article that it was unable to independently corroborate the allegations.

Platner has denied the allegations.

The candidate has also faced criticism for a tattoo that may have links to Nazi military iconography. He has denied having had knowledge of the meaning of the symbol, which features a skull atop crossbones, when he got the tattoo.

Platner is the prohibitive favorite in the Democratic primary against David Costello and Gov. Janet Mills, whose name remains on the ballot despite her dropping out of the race in April. Whoever wins will take on incumbent Republican Collins, who has been in Washington since 1997. The Cook Political Report rated the race as a “toss-up.”

Another contest to watch will be the one determining who will succeed Mills as governor.

The Democratic primary includes Angus King III, an energy executive and son of Sen. Angus King (I-Maine); Maine Secretary of State Shenna Bellows; Hannah Pingree, the former speaker of the Maine House of Representatives who is also the daughter of Rep. Chellie Pingree (D-Maine); former Maine Senate President Troy Jackson; and Dr. Nirav Shah, former principal deputy director of the Centers for Disease Control and Prevention.

Multiple Republicans threw their hat in the race as well: Jonathan Bush, healthcare executive and nephew of former President George H.W. Bush; lawyer Bobby Charles; real estate executive David Jones; Garrett Mason, former majority leader of the Maine Senate; University of Maine System trustee Owen McCarthy; and former Crunch Fitness CEO Ben Midgley.

The Cook Political Report rates the race as likely Democratic.

The House race to pay attention to is the one in the 2nd Congressional District to succeed retiring Democratic Rep. Jared Golden. The presumptive Republican nominee is former Gov. Paul LePage. The Democrats looking to take him on include state Sen. Joe Baldacci, state auditor Matthew Dunlap, former Capitol Hill staffer Jordan Wood, and social worker Paige Loud. The Cook Political Report rated the contest as likely Republican.

Nevada

In the Silver State, voters will cast their ballot for governor, the House, and other elected positions.

Incumbent Gov. Joe Lombardo faces a handful of challengers in the GOP primary including businessman Matthew Winterhawk, BlkEdgeAi executive Donald J. Beaudry Jr., salon owner Irina Hansen, and entrepreneur Jose Zelaya.

The Democratic side includes Nevada Attorney General Aaron Ford, Washoe County Commission Chair Alexis Hill, businessman Emile Bouari, and former radio host Miqehl Bayfield.

A key House race to watch is being held in the 2nd Congressional District, where Rep. Mark Amodei (R-Nev.) is not running for reelection.

Democrats looking to flip the district, which the Cook Political Report calls solidly Republican, include multimillionaire Greg Kidd, former Nevada Assembly Majority Leader Teresa Benitez-Thompson, union representative Kathy Durham, former Nevada Democratic Party Executive Director Matthew Fonken, and seven other candidates. A Democrat has never won the seat.

The Republicans running include business owner David Flippo, ranch manager James Settelmeyer, former police officer George Forbush, and 10 others. President Donald Trump has endorsed Flippo.

South Carolina

Voters in The Palmetto State will cast their ballots for governor, the House, Senate, and a couple state offices.

The GOP gubernatorial primary has attracted the most national attention to the state. Candidates include Lt. Gov. Pamela Evette, Rep. Ralph Norman, Rep. Nancy Mace, South Carolina Attorney General Alan Wilson, and businessman Rom Reddy. Trump has endorsed Evette. The first four are locked in a near dead-heat according to some polls in the state.

Democrats running for governor include state Rep. Jermaine Johnson, trial attorney William Mullins McLeod Jr., and businessman Billy Webster. Whoever wins in November will succeed Gov. Henry McMaster, who is term-limited.

In District 1, several Democrats are vying to replace outgoing Mace.

They include legal assistant Mayra Rivera Vazquez, lawyer Mac Deford, waiter Matthew Fulmer, Navy veteran Nancy Lacore, educator Francina Dantzler, airplane mechanic Max Diaz, and former congressional staffer Ben Frasier.

The Republican primary include former congressional staffer Dan Brown, Dorchester County councilman Jay Byars, Beaufort County Councilman Logan Cunningham, Charleston County Councilwoman Jenny Costa Honeycutt, public accountant Kendal Ludden, doctor Sam McCown, Air Force veteran Alex Pelbath, healthcare professional Cindy Wagers Riley, and funeral home owner Mark Smith.

The Cook Political Report rates the district as solidly Republican, though it was briefly represented by Democratic Rep. Joe Cunningham between 2019 and 2021.

In District 5, Wes Climer is the presumptive Republican nominee while airline worker Andrew Clough and baseball mom Mallory Dittmer are running for the Democratic nod. The winner in November will succeed Norman. The Cook Political Report rates the district as solidly Republican.

North Dakota

Voters in the Peace Garden State will be casting their ballot for the House and a couple state offices.

In the state’s lone House district, incumbent Rep. Julie Fedorchak has a GOP primary challenger in military veteran Alex Balazs. Fedorchak has been endorsed by Trump, while Balazs has the backing of the North Dakota Republican Party. The only Democrat running is Navy veteran Trygve Hammer, who unsuccessfully ran for the seat in 2024.

Fedorchak was first elected in 2024.

The Cook Political Report rates the race as solidly Republican.