‘I’m Speaking’: What Harris’s Top Debate Moments Could Tell Us About Tonight

During the 2020 election cycle, Kamala Harris participated in five Democratic primary debates and, as the vice-presidential nominee, one general-election debate. Her performances in the primary debates showed that she was unafraid to instigate attacks, but could be unsteady when on the receiving end of one.

Her most memorable debate moments were a mix of carefully crafted attacks by and against her during the primary race, and a spontaneous exchange with Vice President Mike Pence that demonstrated what her advisers would like to see again on Tuesday against former President Donald J. Trump.

On Tuesday, Ms. Harris will be judged by how she delivers planned attacks on Mr. Trump and defends herself against his. But her spontaneous reactions to the night’s surprises could well be what voters remember the most.

Here is a look at the three biggest moments that shaped Ms. Harris’s debate performances from the last election cycle and what they might mean for her this time around.

This exchange was carefully choreographed by Ms. Harris and her aides, who believed the only path through the crowded Democratic primary race was to bring down Mr. Biden, the front-runner. With the next fund-raising deadline looming, her campaign also needed a buzzy moment to juice donations and hit its financial targets for the quarter.