Donald Trump’s campaign is preparing a major effort to attack Vice President Kamala Harris if President Joe Biden steps aside as the Democratic nominee, including a wave of ads focusing on her record in her current office and in California, according to two people briefed on the matter.

The Trump team has prepared opposition research books on Harris, and has similar dossiers on other Democrats who could become the nominee if Biden drops out of the race.

But the bulk of the preparations so far have been focused on Harris, including a recently concluded poll testing her vulnerabilities in a general election contest, according to the two people. The Trump team’s attention on Harris is based on its assumption that if Democrats were to bypass the first Black woman to serve as vice president, it would drive even deeper divisions in the party and risk alienating their base of Black voters.