In Georgia, the stakes of the 2020 election could not be higher. Because of the announced resignation of Senator Johnny Isakson for health reasons, both United States Senate seats will be contested.

Yet turning Georgia blue in 2020 remains an uphill battle. That’s because, outside of metro Atlanta and other urban areas like Savannah, Georgia remains a deeply conservative state. The defenders of the demographics-are-destiny thesis should remember that destiny is shaped by history, too.

In many ways, American politics today resemble an earlier era in Southern history, when candidates who only a few years before their election had been dismissed as jokes or nobodies stoked reactionary impulses to win the highest office in the state. That’s what happened in Georgia in 1966 when Lester Maddox, a folksy restaurateur and longtime failed candidate, was elected governor. After Congress passed the Civil Rights Act in 1964, forcing the desegregation of public accommodations in the South, Maddox leapt to public prominence by wielding an ax handle to chase away African-Americans who attempted to eat at his restaurant. He attracted the same voters that George Wallace won in neighboring Alabama — white Southerners embittered by social and political changes that they felt were being forced upon them by sanctimonious, out-of-touch elites.

For several years now, journalists and historians have compared Mr. Trump to George Wallace, but Wallace is just the tip of an iceberg. There is a much deeper tradition of demagogy in American politics — it runs like a bright line through the history of the South — to which Mr. Trump is heir. In Georgia, before Lester Maddox, there was Herman Talmadge, who led the forces of racist reaction following the Supreme Court’s 1954 decision in Brown v. Board of Education. Talmadge supporters in the Georgia legislature altered the state flag to include the old Confederate battle flag as a symbol of Georgia’s defiance of the federal government. Before Herman there was his father, Eugene, a man who stoked some of the pride and a lot of the prejudices of white Georgians to advance his own political interests. In the midst of the Great Depression, when Georgia was among the poorest states in the nation, Eugene tried to build a national campaign by vilifying Franklin Roosevelt’s New Deal, which was the best and only hope that poor Georgians had to pull themselves out of an entrenched poverty that had bedeviled the state and region since the end of the Civil War.

History reminds us that, as repugnant as they are to their political opponents, demagogues like Mr. Trump are not easily defeated. In Georgia, the more that Atlanta’s newspaper editors and influential citizens castigated Eugene Talmadge as corrupt, uncouth and dangerous, the deeper his rural supporters dug in their heels. Ultimately, it wasn’t any moral reckoning that ended political machines like the Talmadges’; it was structural change, when the Supreme Court overturned Georgia’s county unit system, which had given disproportionate power to rural interests.