CNN’s two-night Democratic primary debate will offer a rematch of former Vice President Joe Biden and California Sen. Kamala Harris, whose clash over race became the most closely watched moment of the first round of debates. Biden and Harris will debate in Detroit on Wednesday, July 31.

The debates will also, for the first time, offer a match-up between Massachusetts Sen. Elizabeth Warren and Vermont Sen. Bernie Sanders, the two top progressives in the Democratic primary. The duo — who will debate on Tuesday, July 30 — were not on the same stage during the first debate.