Democratic presidential front-runner Joe Biden appears to have sustained a self-inflicted political wound by telling a black radio host that African Americans considering voting for Donald Trump “ain’t black.” He apparently was referring to his record on civil rights.

A Washington Post columnist, in assessing the flap, wrote that “Biden’s past support for busing” of Delaware students out of their home districts to achieve racial desegregation gave progressive voters grounds to oppose him. In fact, Biden actively opposed school busing for that purpose then, agreeing with white parents there that schoolchildren should not be forced to travel long distances to reduce racial inequality in the classroom.

Biden called such busing “a phony issue which allows the white liberals to sit in suburbia, confident that they are not going to have to live next to blacks.” But he also acknowledged that federal courts had the right by law to counter racial discrimination in the schools, known as de jure integration, while he opposed de facto integration without lawful authority.

The school busing issue was a sticky wicket for Biden from the start. He wrote then that busing “was a liberal train wreck, and it was tearing people apart. The quality of the schools in and around Wilmington was suffering, and they would never be the same. Teachers were going to be transferred without consultation to new school districts.”

Biden also wrote: “I kept introducing legislation to try to keep busing as a last resort, to be used only when school districts had worked actively to segregate children by race.” He drew a line between that attempt and efforts motivated by the desire to alter the racial composition of a school absent a court order. He told a local newspaper: “I oppose busing. It’s an asinine concept, the utility of which has never been proven to me.”

All this, Biden acknowledged, risked muddying his growing reputation as a civil rights champion. “The unsavory part about this is when I come out against busing, as I have all along, I don’t want to be mixed up with a George Wallace,” said Biden, referencing the fiercely segregationist governor of Alabama. “I don’t want anybody to give me credit for sharing any point of view George Wallace has.”

Earlier in the current Democratic presidential race, one of Biden’s challengers for the nomination, Sen. Kamala Harris, scored debating points against him by recalling his Delaware opposition to school busing. Harris said busing had made possible her own grade school education in California. But her attack on him was so politically calculated that it appeared to set back her own presidential ambitions, and her candidacy quickly faded.

Harris has been mentioned as a possible Biden running mate, but the prospect may have been dimmed by the ferocity of that earlier assault.

Biden’s history of opposing school busing in Delaware could raise renewed challenges to his otherwise strong standing as an icon of the civil rights era. So it does not serve his presidential ambition by saying anything to invite renewed examination of his substantial support in the black community.

His ill-advised wisecrack that any African American voter who might vote for Trump “ain’t black” should persuade him to accept quietly the already huge support from that community, and avoid any further verbal gaffes of the sort that have haunted his political career.

Biden’s survival in a third campaign for the presidency has been remarkable, considering his stumbles through the fall and winter prior to his sudden recovery in the South Carolina primary, thanks to its huge black turnout. He will be well served to demonstrate his appreciation for that support in the months ahead without diminishing it with any more wise-guy remarks. He needs instead to articulate his specific plans to extricate the country not only from the coronavirus, but also from the crisis that Donald Trump’s words and deceptions have inflicted on our proud process of self-government.

Jules Witcover’s latest book is “The American Vice Presidency: From Irrelevance to Power,” published by Smithsonian Books. You can respond to this column at juleswitcover@comcast.net.