Progressive wave crashes in Sun Belt battleground as moderate holds his seat

After socialists won a series of Democratic primaries in New York, Colorado and Washington, D.C., the party’s moderate wing has secured what appears to be an increasingly rare victory in Arizona’s 4th Congressional District.

Incumbent Rep. Greg Stanton fended off progressive challenger Kai Newkirk on Tuesday night after months of bitter primary sparring. On the campaign trail, Newkirk accused Stanton of being too pro-business and too pro-Israel — accusations similar to those leveraged by...