The virtual silence from Mrs. Clinton speaks volumes about the complicated place she has occupied as a 1960s Wellesley feminist who stayed as a devoted wife to her husband through infidelities and humiliation.

Forcefully denouncing sexual assault would most certainly provoke ugly attacks on Bill Clinton and Mrs. Clinton’s role in countering the women who accused him of sexual misconduct. That painful past haunted Mrs. Clinton last Sunday when Mr. Trump invited some of her husband’s accusers to the second presidential debate.

In the days since, Mrs. Clinton has had to once again navigate the messy crosscurrents of politics, symbolism and her ambition to shatter “that highest, hardest glass ceiling” of being elected the first female president.

Now, when the collective voice of American women and victims of sexual assault seems to be letting out a cathartic scream, Mrs. Clinton has deferred to another first lady to speak for her. At the San Francisco fund-raiser on Thursday, she pointed to Mrs. Obama’s speech earlier that afternoon when the first lady placed her hand on her heart and spoke out for the many who were outraged.