On July 13, Alabama held a run-off primary for the Republican Party, to determine who the party’s gubernatorial nominee would be. Robert Bentley defeated Bradley Byrne, even though earlier Byrne had been considered the front-runner and the choice of most party leaders.
This Huntsville Times editorial suggests that Democrats voted heavily in the Republican run-off, something that is legal. Democrats did not have a run-off primary. Alabama does not have registration by party. The editorial says the union that represents public school teachers was angry at Byrne, and that the union encouraged its members (most of whom are believed to be Democrats) to vote in the Republican run-off primary against Byrne. Thanks to Ed Still of Votelaw for the link.