PHOENIX (AP) -- Tuesday is primary election day in Arizona, with Republicans deciding their U.S. Senate nominee and voters in both major parties deciding contested races in U.S. House districts.
Polls are open from 6 a.m. to 7 p.m., though early ballots accounted for more than half of the voters cast in the 2010 primary.
Republicans have a four-way race for the nomination for the Senate seat being vacated by Republican incumbent Jon Kyl. He's retiring and not running for a fourth term.
There are contested primary races for one or both major parties in all nine of the state's congressional districts.
U.S. Senator (Republican)
Wil Cardon vs. Jeff Flake -- Winner will face Democrat Richard Carmona in November
An unexpectedly feisty campaign marked by accusations of hypocrisy, broken promises and flip-flopping positions on the emotional issue of immigration draws to a close Tuesday when Arizona voters narrow the field of candidates to replace retiring Republican U.S. Sen. Jon Kyl.
U.S. Congress - Congressional District 1
Democrats -- Ann Kirkpatrick vs. Wenona Benall Baldenegro
Republicans -- Jonathan Paton, Gaither Martin and Patrick Gatti
Paton and Kirkpatrick are considered the front-runners in their respective races.
The district extends from the northern outskirts of Tucson on the south to the Arizona-Utah line on the north. It includes Flagstaff, much of eastern Arizona and a number of American Indian reservations.
U.S. Congress - Congressional District 2
Democrats -- Ron Barber vs. Matt Heinz
Republicans -- Retired Air Force Col. Martha McSally vs. Mark Koskiniemi
This is the first time Barber faces a primary challenge. Heinz says he wants voters to have a choice.
Other Democrats backed out after Gabrielle Giffords announced she was resigning and endorsed Barber as her replacement early this year. Barber won the seat in a June special election against Republican Jesse Kelly.
The 2nd District takes in parts of Tucson and Pima County and all of Cochise County.
U.S. Congress - Congressional District 3
Democrats -- Raul Grijalva, Amanda Aguirre and Manny Arreguin
Republicans -- Gabriela Saucedo Mercer and Jaime Vasquez
Five-term incumbent Arizona congressman Raul Grijalva is facing a rare challenge from within his own Democratic party.
Analysts say Aguirre, a former state legislatior, and Arreguin, a doctor in Tucson, likely don't the financial backing or name recognition to beat Grijalva in the newly redrawn Congressional District 3.
The sprawling district borders Mexico in southwestern Arizona and includes the western half of Tucson, parts of Yuma and portions of several western suburbs of Phoenix. The district became even more solidly Democratic after the boundaries were redrawn from the former Congressional District 7.
U.S. Congress - Congressional District 4
Democrats -- Mike Weisser and Johnnie Robinson
Republicans -- Paul Gosar, Ron Gould and Rick Murphy
Gould touts himself as the leading conservative with more legislative experience. Gosar says he's one of the most accomplished members of Congress who doesn't rule out compromise.
Murphy has stayed out of the fray.
The heavily Republican district runs from western Arizona through Prescott and south of Phoenix.
U.S. Congress - Congressional District 5
Republicans -- Kirk Adams vs. Matt Salmon (Winner will face Democrat Spencer Morgan in November)
They're seeking the seat now held by Rep. Jeff Flake, who is running for a Senate post.
Salmon says he knows how Congress works and has the relationships in Washington to be effective.
Adams says voters are concerned about former members of Congress like Salmon using their government experience to start lobbying careers.
The primary winner will face Democrat Spencer Morgan on Nov. 6.
Spencer doesn't face a primary opponent.
U.S. Congress - Congressional District 6
Democrats -- Matt Jette vs. John Williamson
Republicans -- Ben Quayle vs. David Schweikert
Quayle and Schweikert have been battling for weeks as each seeks a second term. The two were elected to adjacent districts in 2010 but redistricting made Quayle's more competitive and he decided to run in the nearby 6th District.
Each has been the target of heavy negative advertising on television in recent weeks.
The winner of Tuesday's primary will be highly favored to win the seat in November because the district is heavily Republican.
The district includes Scottsdale, Paradise Valley and parts of Phoenix.
U.S. Congress - Congressional District 7
Democrats -- Ed Pastor vs. Rebecca DeWitt (Winner will face Democrat Scott Fistler and Libertarian Joe Cobb)
Pastor, 68, is a fixture in the south Phoenix district and is expected to win easily. He has been in Congress since winning a special election in 1991.
U.S. Congress - Congressional District 8
Republicans -- Trent Franks vs. Tony Passalacqua and Helmuth Hack (Winner will face Democrat Gene Scharer and Stephen Dolgos of the Americans Elect party)
Franks has represented Arizona for nearly a decade in Congressional District 2.
Now, the 55-year-old Republican is seeking the nomination in the state's new Congressional District 8 in Tuesday's primary.
The district takes in the entire northwestern corner of the state including Kingman and Lake Havasu City, but most of its vote is cast in the western Phoenix suburbs. And the district remains solidly Republican.
Franks says his staunchly conservative record makes it tough for other Republicans to challenge him from the right.
Passalacqua says he's also a conservative.
U.S. Congress - Congressional District 9
Democrats -- David Schapira, Kyrsten Sinema and Andrei Cherny
Republicans --Travis Grantham, Wendy Rogers, Leah Campos Schandlbauer, Martin Sepulveda, Vernon Parker, Lisa Borowsky and Jeff Thompson
Arizona's new 9th Congressional District features wide-open primary election races Tuesday for both the Democratic and Republican parties' nominations.
Arizona added a ninth district as a result of population growth recorded by the Census, and the new district takes in much of Tempe and parts of Phoenix, Scottsdale, Paradise Valley, Mesa and Chandler.
There's no incumbent in the race, and the district is regarded as competitive between the two major parties.