Rick Perry's withdrawal from the presidential race and his endorsement of Newt Gingrich give a boost to a campaign that has been gaining momentum in the days before the South Carolina primary. Much of the analysis of this latest turn of events focuses on Mr. Gingrich's surprising attacks on frontrunner Mitt Romney's wealth, his history at Bain Capital, and the low tax rate he pays. But there is another side to Mr. Gingrich's surge that must not escape voters' attention, and that is the nasty racial undertone of the former House speaker's recent attacks on President Barack Obama.

Mr. Gingrich has made the pitch to Republican voters that he is the only one who can go toe-to-toe with the president and knock him out of office, but in Monday's debate, he made clear that his efforts to do so would traffic in some ugly racial stereotypes. Moderator Juan Williams of Fox News (who is black) questioned whether Mr. Gingrich hadn't been belittling African-Americans by implying that they had no work ethic. Rather than softening his earlier remarks, Mr. Gingrich doubled down, calling Mr. Obama "the food stamp president" — to cheers from the audience.

In a single phrase, Mr. Gingrich managed to conflate poverty, welfare dependency and a supposed unwillingness to work among the poor and unemployed with the most bigoted assumptions about African-Americans. It was an appalling performance that could not have been better calculated to appeal to people's worst instincts, made all the more so by Mr. Gingrich's obvious delight in offering up the kind of red meat many in the crowd apparently had been craving all along.

"More people have been put on food stamps by Barack Obama than any president in American history," Mr. Gingrich proclaimed, adding that the president actually wanted people to be unemployed in order to "maximize dependency" on the federal government in Washington. It was a clear echo of President Ronald Reagan's rhetoric about "welfare queens" who drove around in Cadillacs eating steaks and fried chicken — made all the more pointed by the race of the White House's current occupant.

The charge is all the more outrageous because it turns out to be untrue. Several media fact-checkers have documented that the food stamp rolls expanded more underPresident George W. Bushthan they have under President Obama. And in any case, the charge conveniently ignored the fact that Mr. Obama never "put" anyone on food stamps; it was the deepest recession in modern history — which, by the way, began under a Republican administration — that forced millions of poor and out-of-work Americans to sign up for what is officially known as the Supplemental Nutrition Assistance Program, or SNAP, in order to feed their families.

Nor did Mr. Gingrich, when pressed by Mr. Williams, back off his earlier suggestion that poor kids should work as janitors in their schools in order to earn their way out of poverty and develop solid work habits. The idea of fifth-graders spending their school days cleaning toilets and mopping floors to prove they aren't shiftless layabouts is absurd, but Mr. Gingrich insisted it was just the ticket to reducing black poverty. It's hard to imagine a baser, more mean-spirited view of the real needs of poor children.

And for the record, while it's true that a higher proportion of blacks, who make up just 12 percent of the U.S. population, depend on government programs than whites, in absolute terms far more white families than black families take advantage of SNAP and other government assistance, as they have throughout the history of those programs.

But facts are not what concern Mr. Gingrich, who sees South Carolina as his last chance to derail Mr. Romney's path to the Republican nomination. In a state notorious for dirty, racially charged politics, Mr. Gingrich has fallen back on the oldest trick of Southern demagogues, fanning the flames of resentment, fear and divisiveness. South Carolina Republican voters would send a terrible message about their party and its readiness to govern if they fell for it.

Just as disappointing as Mr. Gingrich's vile rhetoric was the fact that none of the other candidates on the debate stage seemed willing to call him on it. Rick Santorum, who is battling Mr. Gingrich to become the conservative alternative to Mr. Romney, even took it as an opportunity to throw in his own two cents' worth of vitriol, prattling on about how the Obama administration encourages black poverty by refusing to affirm the values of hard work, high school graduation and marriage. Were none of the other candidates on stage that night offended by these vicious attacks on minorities and the poor, or were they simply too cowardly to say so in front of what Mr. Gingrich by then had reduced to a hooting mob? Of profiles in courage, there surely were none.

As a student of history, Mr. Gingrich undoubtedly knows that generations of Southern Democrats rose to power on the support of poor whites by stoking racial antipathy, animosity and bitterness. And that since 1968, when Richard Nixon employed a "Southern strategy" to win the White House, Republicans have been mining much the same vein. What a great way to distract attention from the GOP's real agenda of tax cuts for the rich, paid for by eviscerating the social safety net for the middle class and the poor.

Mr. Gingrich apparently thinks degrading images of African-Americans still hold the power to vault him into the nation's highest office. He is mistaken. America may not yet have completely overcome its painful legacy of racial discrimination and injustice, but Mr. Gingrich and others who traffic in such odious views are staking their futures on a past that will never return.