The speed with which these changes are occurring is stunning.

In 2009, when Virginians chose a governor and the customarily sharp, off-year decline in turnout augured a Republican landslide one year after Obama’s win, 78 percent of voters were white and 22 percent minority.

Four years later, the electorate was 72 percent white and 28 percent minority. The makeover contributed to a slender Democratic win for governor that ended a peculiar Virginia tradition: Since 1976, the party that won the presidency had lost the governorship the following year.

The Virginia primaries will be important markers for the political parties, one of which is competitive in high-turnout elections; the other, dominant in thinly attended off-year contests concentrated in gerrymandered districts. The primaries also will measure the pulling power of political personalities, some of whom are preoccupied with keeping their party unified and on-message; others who try but find their party increasingly ungovernable because activists are resentful of authority.

The numbers indicate as much.