California Sen. Kamala Harris and former Vice President Joe Biden are set to face off again in the second round of Democratic presidential primary debates on July 31.

The day before the greatly-anticipated showdown, Sen. Bernie Sanders (I-Vt.) will take on Sen. Elizabeth Warren (D-Mass.) on the first night of the forum July 30.

When Harris and Biden faced off during the first round of the debates, Harris caught Biden off guard when she challenged him on his opposition of busing during segregation.

"As the only black person on this stage, I would like to speak on the issue of race," she said during the debate. "So on the issue of race, I couldn't agree more that this is an issue that is still not being talked about truthfully and honestly," she began, recalling how as a child, a neighbor would not let her children play with her and her sister because of the color of their skin.

She then turned to Biden:

"I do not believe you are a racist," she said. "I agree with you when you commit yourself to the importance of finding common ground. But I also believe, and it's personal, and it was hurtful to hear you talk about the reputations of two United States senators who built their reputations and careers on the segregation of race in this country."

Adding, "It was not only that, but you also worked with them to oppose bussing, and there was a little girl in California who was part of the second class to integrate her public schools, and she was bussed to school every day," she said. "That little girl was me."

Her performance increased public support of Harris, who is now level-pegging with Biden in the polls.