Voters have approved a redistricting plan backed by Democrats, paving the way for a new congressional map that could net Democrats as many as four seats ahead of the midterm elections. The new map expands Democrats' advantage in the state's congressional delegation from 6-5 to 10-1, a significant boost in the race for control of Congress. The referendum represents what's likely the last opportunity for Democrats to pass a new set of congressional lines in their redistricting war with Republicans this cycle. The vote prompted Virginia to shift its midterm primaries from a June election day to August as voters weighed in on the referendum.