[Written in March 2016]
Since the results could come down to California, a detailed look is in order. Trump currently has a 16% lead, but that is potentially misleading, and gets worse.
Each political party in California decides if it wants to allow independents to vote in their primaries. Republicans do not allow independents to decide on Election Day to choose a Republican ballot – the voter must reregister as Republican by May 23 (the election is June 7th)
California has 59 congressional districts. The California delegation will consist of the 3 RNC members, 10 statewide “winner take all” delegates and 3 delegates from each of the 59 districts (winner take all within the district). While Congressional Districts are required to be similar in population, there is a huge difference in the number of Republicans in each district. That means a voter in Orange County has much less influence than a Republican in North Beach in San Francisco. It also greatly increases the motivation for Democrats to register as Republicans in low Republican districts. A few Democratic voters could flip 3 delegates to or away from Trump.