Any missteps heightened the doubts that voters already harbored.

At events for Democratic candidates over the past year, many women said that they were more aware than ever of sexism in their own lives and in the culture at large, because of the #MeToo movement and heightened focus on gender parity. All of that awareness, though, became an obstacle to electing a female president. They knew how sexist the world was, some said, and they couldn’t take the risk.

As they waited for Ms. Warren to arrive at a rally in San Antonio last week, Kathleen Chandler and Amanda Cardoza vividly recalled the moment when Mrs. Clinton lost and how it spurred them to get more involved in politics. Ms. Chandler, 34, held an election night party, she recounted, ordering cookies with pictures of Mrs. Clinton’s face. Deflating balloons clung to her ceiling for a month after the defeat; she couldn’t bear to take them down.

Now, Ms. Chandler saw Mr. Trump’s victory as a sign that Democrats must pick a woman as their nominee. She voted for Ms. Warren.

“Women as leaders can heal better, and our country’s broken,” she said as she fed her young son a bottle. “It’s infuriating that the women are dropping and we’re going to be stuck with white men.”

But Ms. Cardoza, 38, took a different lesson from Mrs. Clinton’s loss. The high school teacher, who wore earrings modeled after Justice Ruth Bader Ginsburg’s collar, was torn between Ms. Warren and Senator Bernie Sanders.

“America hates women,” she said, “I’m sad to say that I think that’s what it is.”

Like Ms. Cardoza, female voters worried the most about the viability of female candidates. Eighteen percent of Democratic women said that a woman could not win the White House, compared with 7 percent of men, according to a CNN poll in January.

In the Super Tuesday contests, Ms. Warren ranked third among female voters, losing to former Vice President Joseph R. Biden Jr. and Mr. Sanders by more than 10 percentage points. She did, however, win 30 percent of white college-educated women, the largest share held by any of the candidates, according to exit polls.