The biggest winner in Tuesday night's primary elections could be President Trump, who flexed his political muscle and exacted revenge on Indiana Republican lawmakers who defied his redistricting push.

Melat Kiros defeated Diana DeGette, who has been in office for as long as the 29-year-old Kiros has been alive.

WSJ’s Aaron Zitner walks viewers through what he’s watching in this year’s off-cycle election, with on-the-ground looks at ...