Republicans took a step towards retaining their majority in the US House of Representatives after a Trump-backed candidate advanced through a "jungle primary" in Washington's 3rd Congressional District, setting up a general election clash with Democratic incumbent Marie Gluesenkamp Perez. The contest is being closely watched as one of several battleground races that will help determine control of the House in November's midterm elections.

Gluesenkamp Perez, who represents the district for the Democrats, will face Republican John Braun after both progressed through the state's non-partisan primary system, in which all candidates compete on a single ballot regardless of party. The race forms part of a wider midterm landscape that also includes four Senate toss-up contests, in Alaska, Iowa, Maine and Ohio, and sixteen House toss-up seats identified by analysts as pivotal to the outcome.