Lt. Gov. David Dewhurst and former Texas Solicitor General Ted Cruz, the two Republican candidates battling one another in a runoff for the U.S. Senate nomination, say the source of their opponent's funding is an important campaign issue. Which campaign is drawing more donations from Texas voters? Which campaign is dominated by money from out-of-state groups? Neither answer is clear-cut. That’s because the Federal Election Commission doesn’t require campaigns to report details about contributions of less than $200 from individuals. The funds raised from these "minor" donors are reported as one lump sum, and are referred to as "unitemized" in...