Dan McLaughlin writes for National Review Online about a challenge linked to Democratic presidential front-runner Joe Biden’s past.

The bedrock of Biden’s support is African-American voters, among whom he led Sanders 50–10 in mid June in a national Economist/YouGov poll, and 50–13 in an early-June battleground-state CBS/YouGov poll, and led Elizabeth Warren 52–14 in a mid June Charleston Post and Courier poll of South Carolina. Most national polls show a similar picture. …

… But in a political culture increasingly focused on past sins against racial and gender equality, Biden has long been sitting on a time bomb: his many enduring friendships and alliances with segregationist Dixiecrats. And by “segregationist,” I don’t mean “not totally on board with the progressive agenda circa 2019”; I mean the real-deal: signers of the pro–Jim Crow Southern Manifesto, “massive-resistance” bitter-enders, raisers of the Confederate flag on public property, you name it. The Senate Democratic caucus Joe Biden joined in 1973 was headed by a former Klansman, with notorious segregationists running virtually all the major committees. These men became Biden’s mentors and friends, and he had nothing but glowing words for them his whole career. …

… Biden can, of course, offer excuses: Some of his old Dixiecrat friends repented; some became Republicans; some were run out of office by liberal challengers. A man ought to say nice things in a eulogy for a friend or a tribute to a retiring colleague, especially those who had showed Biden personal kindness after the death of his wife and daughter in a car accident in late 1972. Then again, some of the men he praised retired unrepentant, and some remained members of the Senate Democratic caucus in good standing well into the 21st century. None of Biden’s excuses would be considered acceptable if he was a Republican like Lott. Biden’s rivals, beginning with Cory Booker and Bill de Blasio, have already started to pounce.