PHOENIX — A challenge to longtime U.S. Sen. John McCain leads the lists of contests drawing attention in Tuesday’s Arizona primary election. Here’s a look at some of the races and issues:

U.S. SENATE

Sen. John McCain is seeking a sixth term, and his main challenger in the Republican primary is former state Sen. Kelli Ward.

McCain is hoping to pull out a large primary victory so he can focus on a general election challenge from Democratic Rep. Ann Kirkpatrick.

Ward has received outside support in recent weeks for an ad campaign attacking McCain, and some state party activists have opposed him, calling him insufficiently conservative. Ward is vowing to “retire” the 2008 GOP presidential nominee Tuesday, the day after he turns 80.

But McCain has been running a strong campaign, drawing support from business and community leaders and retired military officers. A recent CNN poll showed McCain with a wide lead over Ward among likely Republican primary voters.

Scottsdale businessman Alex Meluskey suspended his campaign but still appears on the GOP primary ballot, along with talk-radio host Clair Van Steenwyk.


U.S. HOUSE RACES

All nine U.S. House races are on the ballot, but the top challenges are happening in the 1st, 2nd and 5th districts. The GOP currently holds five seats.

— The 1st District features a slug-fest between five Republicans in the region that runs from Flagstaff to the northern Tucson suburbs currently held by Democrat Ann Kirkpatrick, who is running for U.S. Senate.

— The 2nd District includes parts of Tucson and Cochise County, where two Democrats are fighting for the chance to take on one-term GOP congresswoman Martha McCally, who won by only 167 votes in 2014.

— The 5th District race is essentially a general election contest, since the district that takes in the southeast Phoenix-area suburbs of Gilbert, Queen Creek and parts of Chandler and Mesa is heavily Republican. Four Republicans are running to replacing retiring Rep. Matt Salmon.

The wild card is the 4th District, where Republican incumbent Paul Gosar’s primary opponent is getting strong backing from an out-of-state group. Former Buckeye City Councilman Ray Strauss has benefited from more than $280,000 in spending by the group that seeks to unseat “freedom caucus” members who ousted House Speaker John Boehner.


OTHER TOP RACES

Embattled Maricopa County Sheriff Joe Arpaio is seeking a seventh term and faces former Buckeye Police Chief Dan Saban and two other challengers.

The election comes less than two weeks after a federal judge recommended criminal contempt-of-court charges against the 84-year-old lawman of metropolitan Phoenix for ignoring an order to halt his signature anti-immigration patrols.

Arpaio is a national figure known for his illegal immigration crackdowns and for forcing inmates to wear pink underwear and live in tents outdoors in the summer heat.

The winner will face Democrat Paul Penzone in November.


CORPORATION COMMISSION

In another notable statewide race, five Republicans are vying for three seats on the Arizona Corporation Commission, a utility regulation panel.

Incumbent Bob Burns has been pushing for an investigation of suspected political spending by the state’s largest electric utility, a push opposed by the other candidates. They are commission member Andy Tobin, former state Sen. Al Melvin, state Rep. Rick Gray and retired judge Boyd Dunn.

Two Democrats automatically will advance to the general election.


LEGISLATURE

All 30 state Senate and 60 state House seats are up for election, but just 23 House and Senate races have primary contests. Republicans control majorities in both chambers, but Democrats hope they can pick up three Senate seats in November and win control.


EARLY VOTING/POLLS

It’s too late for voters who receive a ballot by mail to send it back. They must be dropped off at a polling place or elections office or designated drop-off location. Unlike the March presidential primary, voters who cast ballots in person must do so at their assigned precinct. Also unlike the presidential primary, independents are allowed to request either a Republican, Democratic or Green Party ballot at the polls. Only the Libertarian Party has a closed election.

Voters who go to the polls must show identification, either a valid Arizona driver license or ID, tribal identity card or other government-issued identification or a combination from this list: http://www.azsos.gov/elections/voting-election

People can track their early ballots and locate polling places at http://www.azsos.gov/elections. County Recorders officer

Polls open at 6 a.m. and close at 7 p.m. First returns are expected just after 8 p.m.