What to watch: Two of Washington’s 10 congressional districts have competitive races on Tuesday. The primaries will be “top two,” meaning that — as in California — the top two finishers will move on to the general election, regardless of party. Read more

In the Eighth District, four main candidates are running to replace Representative David Reichert, a retiring Republican whose seat is considered a tossup. Former State Senator Dino Rossi, a Republican, is expected to make the top two in the primary. The big question is which Democrat will make it along with him: Shannon Hader, a former official at the Centers for Disease Control and Prevention; Jason Rittereiser, a lawyer; or Kim Schrier, a pediatrician.

In the solidly Democratic Ninth District, Representative Adam Smith, a longtime congressman with a top position on the House Armed Services Committee, is facing a primary challenge from Sarah Smith, a democratic socialist. On the surface, this looks a lot like New York’s 14th District, where another democratic socialist, Alexandria Ocasio-Cortez, beat Joseph Crowley, a longtime congressman with a powerful leadership position. Ms. Smith has encouraged the comparison, while Mr. Smith has emphasized the differences between the two races — including that Ms. Ocasio-Cortez was born and raised in her district, while Ms. Smith lives a bit outside this one.

— MAGGIE ASTOR

Read more about today’s most important races.