High-level campaign staffers for Joe Biden and Kamala Harris engaged in a fiery exchange on Twitter on Wednesday over the candidates' positions on school busing.

The war of words followed the candidates' fiery exchange during last Thursday night's Democratic primary debate in Miami, when Harris challenged Biden over the issue. The face-off produced Harris' "That little girl was me" remark that got wide media attention.

However, Harris' stance on busing isn't rock-solid, at least according to what she told reporters on Wednesday at a Democratic picnic in West Des Moines, Iowa.

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"I think of busing as being in the toolbox of what is available and what can be used for the goal of desegregating America’s schools,” Harris said, but when pressed on whether she believes in federally mandated busing, she responded, "I believe that any tool that is in the toolbox should be considered by a school district.”

That received a sharp response from Kate Bedingfield, Biden's deputy campaign manager and communications director.

"It's disappointing that Senator Harris chose to distort Vice President Biden's position on busing," Bedingfield tweeted, "particularly now that she is tying herself in knots trying not to answer the very question she posed to him!"

That drew a reaction from Harris press secretary Ian Sams, who shot back by quoting Biden when he previously denounced busing.

"VP Biden said: 'Who the hell do we think we are that the only way a black man or woman can learn is if they rub shoulders with my white child?' He called busing an 'asinine concept.' C’mon. Y’all are better than this."

Then Bedingfield answered back: "If we’re cherry-picking quotes on Twitter, what about this one from this January? Sen. Harris: 'I think there are many people who would make a good president... I'm very fond of Joe Biden, so you're not gonna hear me criticize Joe Biden. I think he's a great guy.'"

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"She does think he’s a good guy. So do I," Sams responded. "That’s why a simple 'working with segregationists to stop busing 40 years ago was wrong, and I shouldn’t have done it' would be welcome."

Harris has seen a major surge in the polls since her widely praised performance at last week's Democratic debate. The U.S. senator from California has jumped into third place among the two-dozen candidates seeking the Democratic Party nod in the average of polls, according to Real Clear Politics. Several polls now put her close to Biden.