The Clintons have never understood how to exit the stage gracefully.

Their repertoire has always been deficient in grace and class. So there was Hillary Clinton cold-bloodedly asserting to USA Today that she was the candidate favored by “hard-working Americans, white Americans,” and that her opponent, Barack Obama, the black candidate, just can’t cut it with that crowd.

“There’s a pattern emerging here,” said Mrs. Clinton.

There is, indeed. There was a name for it when the Republicans were using that kind of lousy rhetoric to good effect: it was called the Southern strategy, although it was hardly limited to the South. Now the Clintons, in their desperation to find some way — any way — back to the White House, have leapt aboard that sorry train.

He can’t win! Don’t you understand? He’s black! He’s black!

The Clintons have been trying to embed that gruesomely destructive message in the brains of white voters and superdelegates for the longest time. It’s a grotesque insult to African-Americans, who have given so much support to both Bill and Hillary over the years.

(Representative Charles Rangel of New York, who is black and has been an absolutely unwavering supporter of Senator Clinton’s White House quest, told The Daily News: “I can’t believe Senator Clinton would say anything that dumb.”)

But it’s an insult to white voters as well, including white working-class voters. It’s true that there are some whites who will not vote for a black candidate under any circumstance. But the United States is in a much better place now than it was when people like Richard Nixon, George Wallace and many others could make political hay by appealing to the very worst in people, using the kind of poisonous rhetoric that Senator Clinton is using now.

The last time the Clintons had to make a big exit was at the end of Bill Clinton’s second term as president — and they made a complete and utter hash of that historic moment. Having survived the Monica Lewinsky ordeal, you might have thought the Clintons would be on their best behavior.

Instead, a huge scandal erupted when it became known that Mrs. Clinton’s brothers, Tony and Hugh Rodham, had lobbied the president on behalf of criminals who then received presidential pardons or a sentence commutation from Mr. Clinton.