LITTLE ROCK, Arkansas — The South steps into the spotlight of the 2016 presidential election in this week’s Super Tuesday contests, a delegate-rich day that will highlight the region’s sharp demographic and ideological divides.

In what was once a Democratic stronghold, the party now controls one governor’s mansion, one Senate seat and no legislative chambers from the Carolinas westward to Texas.

The region’s flip to Republican bulwark is steeped in decades-old shifts in the national parties that accelerated under President Barack Obama, who had little connection to white Southerners who used to keep Democrats in power.

That’s left the South a starker, more sharply divided microcosm of the demographic dynamics at play across the country. Republican presidential candidates are fighting for support from a mostly white electorate, including many voters who feel alienated by broad economic and cultural changes. Democrats will depend on growing minority populations and voters clustered in heavily populated urban areas.

In the upcoming Southern primaries, that means Hillary Clinton could sweep the region, but with Democratic electorates that have much larger proportions of African-Americans than those that propelled her husband’s successful 1992 presidential campaign.

The changes have given Republican Donald Trump, hardly a conservative by traditional definitions, an unexpected foothold with voters. Trump has campaigned through the South with a rallying cry that long has resonated in the region. “The silent majority is back!” he declared.

Trump’s rhetoric harkened back to Richard Nixon’s “Southern strategy,” a concerted effort to bolster support from working-class white voters in the elections that followed passage of the 1964 Civil Rights Act. Nixon made frequent references to the “silent majority” and the “forgotten majority.”

To Richard Fording, chairman of the political science department at the University of Alabama, there are similarities in the angst Nixon saw brewing in the Southern electorate a half-century ago and what Trump is tapping into now. Exit polls from last week’s Republican primary in South Carolina showed that Trump can draw votes from the evangelical Christians and social conservatives.

Unlike Trump, Hillary Clinton’s ties to the South run deep. She spent 12 years as the first lady of Arkansas and was active in the state during her husband’s tenures as governor. But the political shifts across the region have dramatically remade the Democratic electorate she faces on Super Tuesday.

When Bill Clinton was on the ballot in the 1992 Democratic primaries, the electorate in Georgia was 70 percent white and 29 percent black. In Alabama that year, the Democratic primary electorate was 76 percent white and 23 percent black.

By 2008, exit poll data from Democratic primaries showed a dramatic shift of whites away from the party in Southern states. In Georgia, 42 percent of voters were white and 52 percent black. In Alabama, it was 44 percent white and 51 percent black.

The conservative Democrats who once represented the South in Congress and in governor’s mansions have disappeared.