Just a couple sunny days remain before votes are counted in Tuesday’s primary, which will set the table for key congressional and legislative races this fall.

Washington Secretary of State Kim Wyman’s office is “bravely” predicting 40 percent turnout, according to spokesman David Ammons.

That’s based on the average of the last two midterm primaries. But Ammons noted that other states have seen dismal turnouts this year. And unlike the past two midterms, there is no U.S. Senate race on the ballot.

Ballots in the all-mail election must be postmarked by Election Day or deposited in a ballot drop box by 8 p.m.

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In Seattle, voters will decide the fate of a controversial plan to create a Metropolitan Park District with the authority to raise property taxes to fund parks.

Most of the action in congressional and legislative races this year will be reserved for the general election, but candidates in a few crowded contests are going all out to ensure they make it to November.

The most competitive congressional race is in Eastern Washington’s 4th District, where a dozen candidates — eight Republicans, two Democrats and two independents — are campaigning to replace retiring Republican U.S. Rep. Doc Hastings.

On the Republican side, Dan Newhouse, a farmer and former director of the state agriculture department, has garnered the most financial support and endorsements. Former NFL player and two-time statewide candidate Clint Didier and state Sen. Janéa Holmquist of Moses Lake are also in the running.

The biggest question for Tuesday is whether two 4th District Republicans will advance to November, or whether the crowd of conservative candidates will divide the vote enough to allow a Democrat onto the fall ballot.

Among Democrats, Estakio Beltran, a former aide to U.S. Sen. Maria Cantwell, has landed the most support from party leaders. But Tony Sandoval, a longtime Yakima political activist, could divide the sparse Democratic vote in the heavily Republican district.

Under Washington’s open primary system, the top two vote getters in each race advance to the general election, regardless of party affiliation.

In the 1st Congressional District, the primary will be an early test for Republican Pedro Celis, the GOP’s favored candidate to challenge first-term U.S. Rep. Suzan DelBene, D-Medina.

Although there won’t be much drama in the primary-election outcome of most state legislative races, a few are worth keeping an eye on Tuesday.

In the 37th Legislative District of Southeast Seattle and Renton, six candidates are competing for the open seat created by the retirement of Democratic state Sen. Adam Kline.

Pramila Jayapal, a prominent immigrant-rights activist, has sewn up virtually every major Democratic endorsement for the seat, including a shoutout from famed feminist Gloria Steinem. Other Democrats fighting for a November ballot spot are: Louis Watanabe, who taught business at Bellevue College; civil-rights attorney Sheley Secrest; substitute teacher John Stafford; and retiree and activist Claude Burfect. The lone Republican in the race is Boeing employee Rowland Martin.

Ethics and corruption allegations are flying in the 31st Legislative District of Southeast King County and Northeast Pierce County, where state Sen. Pam Roach, R-Auburn, faces a challenge from fellow Republican state Rep. Cathy Dahlquist, R-Enumclaw. But a little-known Democrat, Lynda Messner, also is in the race and could cut short the looming Dahlquist-Roach showdown if she captures enough votes Tuesday.

Control of the state Senate — ruled this year by a coalition of 24 Republicans and two Democrats — is the biggest legislative prize being fought over by Democrats and Republicans this year.

Business interests already have poured more than $160,000 into the 35th Legislative District to support state Sen. Tim Sheldon, a Democrat who has been disowned by his party for joining the Republican-dominated Senate majority coalition.

The independent expenditures backing Sheldon, funded by realtors, restaurant groups and others, come as he’s being squeezed by challengers from the right and left: Republican Travis Couture and Democrat Irene Bowling.

In Seattle, meanwhile, supporters of socialist Jess Spear are looking to the primary as an early measure of her campaign against Democratic House Speaker Frank Chopp in the 43rd Legislative District.

As the only candidates on the ballot, both Spear and Chopp will advance, but the primary could give some indication of whether Chopp has anything to worry about.

Jim Brunner: 206-515-5628 or jbrunner@seattletimes.com. On Twitter @Jim_Brunner