Julian Castro, the mayor of San Antonio, who delivered the keynote address on the opening night of the Democratic National Convention on Tuesday, is part of a new generation of Democrats seen as capable of breaking the GOP grip on statewide office. (Andrew Geraci/ The Washington Times)

Julian Castro, the mayor of San Antonio, who delivered the keynote address on the opening night of the Democratic National Convention on Tuesday, is part of a new generation of Democrats seen as capable of breaking the GOP grip on statewide office. (Andrew Geraci/ The Washington Times)