The 2nd District is a perennial battleground, and Donald Trump-backed former police officer is the likely Republican nominee to take on Democratic Rep. Gabe Vasquez.

Primaries for Senate and U.S. House determine which Democrats and Republicans face off in the November election.

The highest-stakes race in Iowa on Tuesday is the Democratic primary for Senate, in which two state lawmakers — Josh Turek and Zach Wahls — have argued they are the best person to flip a seat held by ...