The donor, Susie Tompkins Buell, who has spent millions on liberal causes, said Mr. Franken’s fellow senators “moved too fast” in calling on him to resign.
Ms. Gillibrand, a senator from New York, has seen her rising star lifted higher by her run-ins with President Trump over his treatment of women.
After purging some from their ranks, Democrats intensify a push to investigate the president over accusations of harassment and abuse.
In a coordinated campaign, at least a half dozen Democratic women in the Senate called on their colleague, Senator Al Franken of Minnesota, to resign.
Ms. Gillibrand spoke with Jennifer Steinhauer about her legislation to reform policies on sexual harassment on Capitol Hill, power dynamics, President Bill Clinton and more.
It was a remarkable statement from a senator who enthusiastically backed Hillary Clinton’s presidential bid last year but has been deeply involved in efforts to curb sexual abuse and harassment.