Want to know if a red wave is happening? Watch this special election next week

A special election here next week could offer Democrats a preview of the pain coming their way in November. Or it could provide powerful evidence that a Republican wave election is not in the offing.

Both parties are dumping money into this Hudson Valley district to notch a short-lived but symbolic victory in the last competitive race before the midterms. The winner will succeed Democrat Antonio Delgado for just a few months. But the messaging, turnout and margin of the contest will offer tea leaves into what lies ahead this...