Early-state polling shows Ms. Warren with an edge among female voters but Mr. Biden with more backing over all. Nationally Mr. Biden leads among female voters, a reflection of his strength in the race.
At events for Ms. Warren and Ms. Klobuchar in recent months, female voters were grappling with contradictory ideas. They thought the women were better equipped to run the country but worried the country was too sexist to elect them.
Chatting with fellow volunteers for Ms. Warren after a campaign event on Sunday, Diane Lemker, 65, bemoaned what she saw as unfair political projection by others.
“‘I don’t know if people over there are ready for a woman, so we can’t vote for a woman.’ Oh my gosh!” she said. “With my support of her, I am not only affirming that women are capable, but I am also actively rejecting the undercurrent of misogyny.”
Some frustrated supporters of Ms. Warren argue the concerns about electability have become a self-defeating prophecy for women.
“It’s just disheartening to think we could have come together, and now maybe people think women are getting too much power, or too much strength in the numbers, that they’re getting a little bit afraid,” said Erin Smith, 19, as she waited with friends for Ms. Warren to address a crowd in Marshalltown, Iowa.
Aileen Bell, 21, agreed, saying gender was part of what drew her to Ms. Warren.
“If I’m going to choose between an old white man and a woman, and we’ve never had a woman in the White House, I feel much more drawn to the woman on the stage,” said Ms. Bell, a student who attended the first Women’s March. “If we don’t run women, then we’re never going to have a woman in the White House.”