These are the biggest primary races to watch tonight

MAINE

Demcrat Senate Primary

Politically embattled oyster farmer and Marine veteran Graham Platner is not facing a particularly strong challenge on the primary ballot Tuesday night after Maine Gov. Janet Mills dropped out of the race. Platner is expected to walk away with the nomination tonight but will face an uphill battle against long-term Republican incumbent Susan Collins. Recent controversies cloud his campaign inlcuding a recent New York Times article with former partners detailing a history of abuse and addiction in Platner.

District 2

With Rep. Jared Golden opting not to seek reelection, Maine's 2nd Congressional District is open for the first time in years. Democrats are choosing a nominee in a competitive primary, while Republicans are looking to reclaim the rural, Trump-friendly district in November, per WGME. The seat is expected to be one of the more closely watched House races in November.

NORTH DAKOTA

House

While Republicans congrewoman Julie Fedorchak is heavily favored to hold on to North Dakota's lone congressional seat, the GOP primary remains a key test of influence within the party. With the state remaining one of the nation's most reliably conservative strongholds, the winner of the primary will enter the general election as the clear favorite, per AP.

NEVADA

Governor

Tuesday, Democrats are choosing a nominee to challenge Republican Gov. Joe Lombardo, a vulnerable incumbent. The general election will largely hinge on turnout and enthusiasm, as incumbent governors are difficult to unseat. The primary has drawn significant attention as Democrats look to unite behind a candidate capable of reclaiming the governor's mansion in this battleground state. While the eventual nominee will face the difficult task of unseating Lombardo, the primary offers a early test of Democratic enthusiasm before November.

SOUTH CAROLINA

Senate

Republican Sen. Lindsey Graham faces a primary challenge from candidates seeking to capitalize on conservative dissatisfaction with the longtime incumbent. While Trump-backed Graham, per Fox News, remains the favorite, the race is being watched closely for signs of division within the party and the effectiveness of Trump's endorsement.

Governor

With current Gov. Henry McMaster term-limited from running again in the deep-red state, the Republican primary is a crowded one. The contest has drawn national attention after President Donald Trump weighed in, endorsing Lt. Gov. Pamela Evette over Trump ally and Congresswoman Nancy Mace, per The Hill. The endorsement is another test of Trump's influence within the state.