Are Democrats maneuvering to “replace” existing American voters with immigrants from Latin America? When Fox News personality Tucker Carlson made that claim in April, an awful lot of people went ballistic.

“The Democratic Party is trying to replace the current electorate, the voters now casting ballots, with new people, more obedient voters from the Third World,” Carlson said on Fox News Primetime. “That’s what’s happening…. If you change the population, you dilute the political power of the people who live there. So every time they import a new voter, I become disenfranchised as a current voter.”

On his show a few days later, Carlson doubled down.

“Demographic change is the key to the Democratic Party’s political ambitions,” he declared. “In order to win and maintain power, Democrats plan to change the population of the country.” He contended that “when you change who votes, you change who wins,” which is why “our leaders have no right to encourage foreigners to move to this country in order to change election results…. Mass immigration increases the power of the Democratic Party, period. That’s the reason Democrats support it.”

Carlson is not the first conservative to rail against immigration on the grounds that the newcomers will vote Democratic. In a 2017 column headlined “Yes, Virginia, Immigration Is Turning The Country Blue,” for example, Ann Coulter wrote that “Democrats want a never-ending stream of Third World immigrants … because they know immigrants will help them win elections.” Similarly, when Republicans in Virginia lost seats in 2019, right-wing commentator Laura Ingraham blamed the results on immigration: “Immigrants are more likely to vote Democrat,” she said, and had “dragged the electorate to the left. It’s just a fact of life.”

To be fair, voices on the left have said much the same thing.

In their influential 2002 book, The Emerging Democratic Majority, liberal strategists John Judis and Ruy Teixeira made the case that Democrats were poised to dominate US politics for years to come, in part because of immigration-fueled demographic change. “Hispanic support is a crucial part of a new Democratic majority,” they wrote, and “Hispanics are the minority group that is growing the most in terms of both absolute numbers and percentage of population.”

On his program, Carlson played a 2013 clip of then-San Antonio Mayor Julian Castro forecasting a coming era of Democratic dominance in Texas, powered in part by rising numbers of Hispanic voters. “It’s changing,” Castro exulted. “It’s going to become a purple state and then a blue state because of the demographics, because of the population growth of folks from outside of Texas.”

This has long been conventional wisdom. “For years, the Democratic Party has operated under one immutable assumption,” wrote Zack Stanton in Politico last fall. “Long-term demographic trends would give the party something like a permanent majority as the country as a whole grows less white and more urban.”

But as is so often the case, real life isn’t lining up with the ideologues’ predictions.

Conservative fears and progressive hopes notwithstanding, the rise of Hispanics is not leading to the decline and fall of Republicans. Last week, voters in the overwhelmingly Hispanic border city of McAllen, Texas, elected as mayor the former chairman of the local Republican Party. In the presidential election last fall, Donald Trump flipped five Hispanic-majority Texas counties to the GOP, part of a nationwide surge of Hispanic voters away from the Democratic Party. Zapata County, with a 94 percent Hispanic population, had not supported a Republican presidential candidate since 1924.

Texas wasn’t an outlier. In Arizona, Florida, New York, and California, Hispanic voters swung dramatically toward the GOP. All told, one-third of the Hispanic vote went Republican last year — considerably better than the Republicans’ showing in 2016. Nor was the phenomenon restricted to Hispanics. Even in heavily Democratic big cities like Chicago, New York, and Philadelphia, a detailed New York Times analysis showed, precincts with large populations of Asian, Eastern European, and Arab immigrants also shifted markedly from blue to red.

What happened to Republicans being “replaced” by foreign-born voters? To the Democrats’ locked-in demographic advantage?

The answer is that politics is fluid, elections are multitudinous, and voter behavior is often too complicated and subtle to be reduced to group identity. Ethnicity doesn’t determine elections — ideas do. And as Democrats have been realizing to their chagrin, the ideas embodied in Republican campaign messaging turn out to have a powerful appeal to many foreign-born and nonwhite voters.

“We’ve ended up in a situation,” Democratic data guru David Shor told New York magazine in March, “where white liberals are more left wing than Black and Hispanic Democrats on pretty much every issue: taxes, health care, policing, and even on racial issues or various measures of ‘racial resentment.’” Did anyone foresee that by tying itself more tightly than ever to issues of racism and racial equity, the Democratic Party would push more nonwhite voters away? Perhaps not, but that’s what happened.

For a political party to take the support of demographic groups for granted is dumb; for a party to take for granted the hostility of those groups is even dumber. Neither Democrats nor Republicans own the votes of immigrants, no matter how vehemently TV hosts and other partisans insist otherwise. One of the glories of our political system is that demography isn’t destiny.

(Jeff Jacoby is a columnist for The Boston Globe).