Mr. Biden, go Cheney yourself:

Joseph R. Biden Jr. on Wednesday lashed out at his Democratic rivals who had condemned his fond recollections of working relationships with segregationists in the Senate, declining to apologize and defending his record on civil rights. The angry exchange shattered, at least for now, the relative comity that had marked the Democratic presidential primary.

Until Wednesday, many of the Democratic candidates had largely taken oblique swipes at Mr. Biden, while the former vice president sought to stay above the fray, training his sights on President Trump instead.

But a day after he invoked the 1970s, an era when he said he could find common ground with other senators — even virulent segregationists — his opponents offered their sharpest criticism yet.

Senator Kamala Harris of California said the former vice president “doesn’t understand the history of our country and the dark history of our country,” and Senator Cory Booker of New Jersey said Mr. Biden should immediately apologize for using segregationists to make a point about civility in the Senate.

Ms. Harris and Mr. Booker, who are both black, were not alone: Other candidates including Senators Elizabeth Warren of Massachusetts and Bernie Sanders of Vermont also weighed in with criticism. And even some of Mr. Biden’s senior campaign advisers were privately shaken by his remarks.

Yet for much of the day, Mr. Biden and his campaign appeared publicly unbowed and intent on defending, or at least explaining, his worldview of politics, which is rooted in his early days in the Senate when, he said, legislators who disagreed still worked together. He cited two defenders of segregation, Senators James O. Eastland of Mississippi and Herman E. Talmadge of Georgia, to make that point.

I get it:  Biden was bragging about how he could work with evil bigots to throw black people in jail and keep them for segregating schools.

This is not something to brag about.