With the presidential race a dead heat two weeks before Election Day, Vice President Kamala Harris is moving aggressively to make sure voters in the battlegrounds remember precisely why they rejected Donald J. Trump four years ago.

Gone is the euphoria of her joyful first weeks as the Democratic presidential nominee. She is no longer trying simply to diminish the former president. Now, he looms large. Literally.

“See for yourself,” she told a crowd in Ashwaubenon, Wis., on Thursday, gesturing to two large television screens installed at the rally. “Let’s roll a clip.”

The video screens lit up with a 40-second montage of Mr. Trump bragging about overturning Roe v. Wade.

As Ms. Harris stood watching like a late-night host observing the audience’s reaction, the crowd booed and then began a chant of “Lock him up.” She gently stopped them before returning to her promises to restore and protect abortion rights.

Deploying his words as her sharpest weapons, Ms. Harris is pointing to Mr. Trump’s erratic behavior and increasingly outlandish and antidemocratic statements to paint him as unfit, unstable and, above all, too dangerous for another term. It is a closing argument she is hoping will persuade the dwindling number of undecided voters to help her defeat him.