The next test of who Democratic voters want to see leading the party will take place Tuesday in southwest Arizona, where three leading candidates are offering competing visions in the primary to fill the late Rep.

While Tuesday's special election in Arizona may not seem like the type of story to generate nationwide headlines, the race is getting eyes across the country for boiling down the current state of the Democratic Party into a single election.

Adelita Grijalva is the front-runner to replace her father in Congress but faces an unexpectedly competitive primary featuring a young social-media-savvy newcomer.