Voters in New York, Utah, Oklahoma, Maryland, and Colorado will be casting their ballots, and South Carolina and Mississippi will be holding runoffs for races that were too close to call earlier this year.

Here are the biggest races to watch out for:

Governor races in Colorado, Oklahoma, and Maryland

Colorado is holding an open gubernatorial primary, in which voters can cast their ballot for candidates of either party. The Democratic incumbent, John Hickenlooper, is term-limited so he cannot seek re-election. Four candidates in each party are running to succeed him; polls suggest that a Democrat will ultimately emerge the winner in November.

In Oklahoma, the incumbent governor, Mary Fallin, is also term-limited. She is a Republican and largely unpopular. But Oklahoma, as a deeply red state, is likely to elect another Republican governor. The only question is which candidate among the ten Republicans running in Tuesday’s primary will advance to November’s general contest. (Oklahoma will also be voting on whether to legalize medical marijuana on Tuesday.)

Democrats in Maryland have several gubernatorial candidates to choose from on Tuesday—eight, to be specific. Whoever wins will face an uphill battle, challenging incumbent Gov. Larry Hogan in November. Hogan, despite being a Republican in a largely blue state, is widely popular.

Red-to-blue?

Tuesday is the latest chapter in the Democrats’ bid to win back the House, but few of the Republican-held seats on the ballot Tuesday are considered vulnerable. One exception is Colorado’s 6th district.

Incumbent Rep. Mike Coffman, a Republican who’s held the seat since 2009, is seeking re-election. But as the state and the 6th district turn increasingly blue, he’s considered at-risk of losing to a Democrat in November. Tuesday’s primary will determine who he faces in the midterm. Attorney and Army veteran Jason Crow is battling it out with former Obama administration official Levi Tillemann for the Democratic nomination. Crow is widely expected to defeat Tillemann and has the backing of the party.

Romney’s return

In Utah, former Massachusetts governor and presidential candidate Mitt Romney is running to fill the seat vacated by outgoing Sen. Orrin Hatch. Romney is favored to win the seat in the November midterms, but he failed to secure the Republican nomination outright in April, so he will face state Rep. Mike Kennedy in Utah’s primary Tuesday. The winner will go up against Democrat Jenny Wilson in the general.

Bonus: the start of a political career for Chelsea Manning?

Chelsea Manning, the government whistleblower and former intelligence analyst, is challenging two-term incumbent Sen. Ben Cardin in Maryland. Manning, whose prison sentence for leaking classified information was commuted by President Barack Obama, announced her candidacy in January, but her campaign has faltered since then.