Some of Arizona's biggest races will be largely decided in the primary election

It's Election Day in Arizona, and many of the biggest races in the state will be decided in Tuesday's Democratic and Republican primaries.

Why it matters: Two hotly contested U.S. House races, a plethora of legislative races and some noteworthy county contests are happening in districts that are dominated by one party or the other, which means today's vote is likely the only one that matters.

• Some municipal races will also be over after Tuesday if candidates get the outright majorities they need to avoid runoffs in November.
• And in other races, the primary will set up blockbuster general election matchups.

At the congressional level, there are four big races to watch:

CD1 Democrats: Six Democrats are vying for a chance to take on seven-term Republican U.S. Rep. David Schweikert in this highly competitive district in north Phoenix and Scottsdale.

• The candidates are: Andrei Cherny, Marlene Galán-Woods, Andrew Horne, Kurt Kroemer, Conor O'Callaghan and Amish Shah.
• Schweikert won by about 3,200 votes in 2022.

CD2 Republicans: First-term incumbent U.S. Rep. Eli Crane was one of eight Republicans who voted to oust former Speaker Kevin McCarthy .

• Now, Crane faces a GOP primary challenge from former Yavapai County Supervisor Jack Smith, who's backed by a group with ties to McCarthy .
• The winner will face Democrat Jonathan Nez, the former Navajo Nation president, in the predominantly Republican, rural Arizona district.

CD3 Democrats: The race to replace incumbent U.S. Rep. Ruben Gallego, who's running for U.S. Senate, is largely a two-way contest between former Phoenix City Council member Yassamin Ansari and former state legislator and ex-Arizona Democratic Party chair Raquel ​​Terán.

• ​​Terán led in outside spending for much of the race, but a pro-cryptocurrency super PAC spent more than $1.3 million in television ads for Ansari in the final weeks of the campaign.
• The south and west Phoenix-based district is overwhelmingly Democratic, so the winner is effectively guaranteed to win the seat in November.

CD8 Republicans: Six candidates are on the primary ballot in this solidly red West Valley district, including five prominent Republicans. But the race has largely been defined by the nasty slugfest between Abraham Hamadeh and Blake Masters .

• Masters has run attack ads against Hamadeh that highlight his Muslim background.
• Former President Trump last December endorsed Hamadeh over Masters. He backed both in 2022, when they ran for attorney general and U.S. Senate, respectively.
• But last Saturday, Trump announced that both candidates have his "complete and total endorsements." Ohio U.S. Sen. JD Vance had endorsed Masters long before becoming Trump's running mate.

Meanwhile, Kari Lake is widely expected to easily win the GOP nomination for U.S. Senate against underdog Mark Lamb, the sheriff of Pinal County.

Several big primaries could determine the future of Maricopa County governance for the next four years:

Recorder: Embattled Republican incumbent Stephen Richer, who's at loggerheads with election deniers in his party over his defense of the county's election system, faces a three-way primary in his re-election.

• He goes up against state Rep. Justin Heap and information management technology professional Don Hiatt.
• The winner will compete with Democrat Timothy Stringham in November.

County attorney: Incumbent Rachel Mitchell faces challenger Gina Godbehere in the Republican primary.

• Democrat Tamika Wooten will go head-to-head with the winner in the general election.

Sheriff: Both parties have contested primaries.

• Russ Skinner, a Republican-turned-Democrat who was appointed to replace former Sheriff Paul Penzone, faces former Phoenix police officer Tyler Kamp in the Democratic primary.
• Retired Glendale police officer Mike Crawford, former Mesa police chief and Department of Public Safety director Frank Milstead, and former Maricopa County Sheriff's Office chief deputy Jerry Sheridan face off for the GOP nomination.

Board of supervisors: There are contested Republican primaries for two open seats, while two incumbents seeking re-election also face challengers in the GOP primary.

State legislature: With few genuinely competitive districts in play in November, the majority of Arizona's 90 legislative races will be decided in the primary.