With feminists stumping for Hillary Clinton and pundits pondering Bernie Sanders' strength with Democratic women, most of the focus on female voters in 2016 has been on the left. However, right-leaning and independent women will play just as critical a role in the outcome of the GOP primary and the general election.

Topline polling numbers might suggest on first glance that GOP women and men don't have dramatically different preferences. But a more detailed look at the data shows that women's votes could make the difference in the Republican nomination. If the field concentrates, so will women's support, and not behind Donald Trump.

According to the latest Fox News poll, 39 percent of GOP voters in South Carolina say they would never support Trump. Among women, it's even worse: a whopping 42 percent of GOP women refuse to support Trump. The same trend is reflected in national polls, and this will limit Trump's ability to make gains as the field narrows.

If the race were among just front-runners Marco Rubio, Donald Trump and Ted Cruz, Rubio would have a slight edge among all GOP voters with candidates earning 34, 33, and 25 percent respectively, according to Public Policy Polling. Men would put Trump in first place, but that doesn't matter: Rubio is carried to first place overall by female voters, who would choose Rubio 39 percent of the time, compared to 28 percent for Trump and 23 percent for Cruz.

As the field currently stands, women's support is divided: In addition to Rubio, Ben Carson gets most of his support from female voters. John Kasich has equal support among men and women.

All GOP campaigns should examine what factors are leading to their challenges or successes with the fairer sex. One thing is obvious: It cannot help Trump that he's used foul, sexist language and engaged in personal attacks on popular conservative women like Carly Fiorina or Megyn Kelly.

Cruz, who appeals to more men than women, is a tougher case: He has painted himself as the most extreme conservative in the race. His electoral strategy is to activate the conservative base rather than attract new or independent voters. This branding and strategy affect his tone, which could be off-putting to many women.

Meanwhile, in stark contrast, Rubio, Carson and Kasich all stress unity, optimism, inclusiveness and outreach. In general (with some exceptions), more women see these candidates as honest and trustworthy, and more women say these candidates care about the needs and problems of people like them.

Let's consider the consequences for the general election: If a GOP candidate lacks support from women inside of his own party, that's not a good omen for November. Women voters comprise an even greater share of the total voters in the general election (53 percent) than in the GOP contests (48 percent, according to exit polls from Iowa and New Hampshire). GOP candidates can't afford to perform poorly with women by a large margin if they hope to win the general election.

If Trump becomes the nominee, his woman problems will follow him into the general contest. According to the latest Quinnipiac poll, Sanders would resoundingly defeat him if the vote were held today due to a giant 16-point gap with women voters. Trump and Clinton would nearly tie overall, because while Trump wins men by 9 points, he loses women by the same margin.

Cruz faces a similar challenge. He would also lose a general election to Sanders because he would lose women by 16 points. Cruz is only able to edge out Clinton because he closes the gender gap with her to only 4 points.

Rubio does the best job among the three GOP front-runners garnering female votes in a general election. He manages to reduce the gender gap to single digits facing both potential Democrats: He would both lose women to Sanders by 9 points – meaning he still has some work to do appealing to women voters – but he actually polls 1 point ahead of Clinton with women.

Republicans would be wise to consider the female vote, given their party's recent difficulty winning over women in the general elections of 2008 and 2012, when Obama carried women by 13 points and then 11 points. Losing among women by such margins is the reason the GOP does not control the White House today.

Narrowing the gender gap is a necessary step if Republicans want to take back the presidency. Voters and candidates should consider this during the important primary season.