From the day Ms. Warren announced her plan to skip traditional fund-raisers in February, she had said the pledge only applied to the primary. “I do not believe in unilateral disarmament,” she said then on MSNBC.

But she told CBS News in an interview posted on Tuesday evening that, even as President Trump has set fund-raising records, she would not change how her campaign raises money if she won the Democratic nomination.

“No, I will not be forced to make changes in how I raise money,” Ms Warren said. “Look, for me this is pretty straightforward. Either you think democracy works and electing a president is all about going behind closed doors with bazillionaires and corporate executives and lobbyists and scooping up as much money as possible. Or you think it’s about a grass-roots, let’s build this from the ground up.”