“I think we’ll see a lot of women walk away from the party over this,” a Republican consultant says. The crowd in Kinston, N.C., as Donald J. Trump delivered remarks on Wednesday. Stephen Crowley/The New York Times

Donald J. Trump has polarized men and women, with the sexes parting ways to such a degree that Election Day could produce the biggest gender gap in decades.

And now that division is being amplified by a gender war in the Republican Party itself. Men and women are taking sides over accusations of Mr. Trump’s mistreatment of women, with the latest flash point a blistering exchange between Newt Gingrich and Megyn Kelly of Fox News.

Increasing numbers of Republican women have turned on their party’s male leaders for defending Mr. Trump against accusations that he groped or forcibly kissed more than 10 women. Many are complaining publicly that for years they stood up for the party against Democrats who accused it of pursuing a “war on women.” They are unable to do so any longer, they say, and they see hypocrisy in Republican men rallying behind Mr. Trump after the same leaders for years accused Bill Clinton of predatory behavior.