Alaskans vote Tuesday in a primary that's first local test of discontent that fueled Trump and Sanders

Alaska voters head to the polls Tuesday for the state's primary election, where they'll give their first hints about how far the discontent that fueled the rise of Donald Trump and Bernie Sanders has trickled down.

Fifty Alaska House and Senate seats are up for re-election, though only 22 primary races feature more than one Republican or Democrat — and of those, only about a dozen are expected to be close.

Polls are open from 7 a.m. to 8 p.m.

Among the most expensive campaigns is the three-way GOP race in District L to replace retiring Anchorage Republican Sen. Lesil McGuire. The hopefuls are telecommunications salesman Jeff Landfield, former Anchorage School Board member Natasha von Imhof and Rep. Craig Johnson, who is leaving his House seat.

[Alaska primary election is Tuesday: How and where to vote, who you can vote for and what the turnout's looking like]

In two rural districts, the Alaska Democratic Party has recruited two challengers running to the left of Democratic incumbents who caucus with the House's Republican-led majority, Ben Nageak of Barrow and Bob Herron of Bethel.

The state Republican Party, meanwhile, is targeting one of its own incumbents, Rep. Jim Colver of Palmer, who party leaders say has been too cooperative with House Democrats.

Colver and Rep. Paul Seaton, R-Homer, are both facing primary challenges and fending off attacks by conservative groups that say they've strayed too far from the party line.

House Democratic minority members hope that Tuesday's election will be the first step toward a new majority coalition organization that will include Republicans and urban Democrats — not just the Republicans and Bush Democrats who make up the current House leadership and ruling caucus.

[From driving to flying to burning tires: How Alaska's candidates spent their penultimate day of campaigning]

At the federal level, Republican U.S. Sen. Lisa Murkowski is seeking her third full term and hopes to defeat a trio of challenges from Bob Lochner, Paul Kendall and Thomas Lamb.

On the Democratic side are two candidates, Edgar Blatchford and Ray Metcalfe.

U.S. Rep. Don Young faces three Republican primary challengers, while three others seek the Democratic nomination, including retired public radio executive Steve Lindbeck — by far the best-funded of the lot.