In the general election battle for female voters, Republican Mitt Romney's campaign is testing a new strategy contrasting Ann Romney and her brood of boys against President Obama's family of girls.

"I hate to say it, but often I [felt like I] had more than five sons," Ann Romney, the wife of Obama's likely opponent in November, says in a new ad. "I had six sons, and [Mitt] would be as mischievous and as naughty as the other boys," she says as decades-old photographs of the Romneys flash across the screen with the message, "Ann and her '6 boys.'"

Up until three months ago, Mitt Romney was running neck-and-neck with Obama in support among independent women from key swing states, according to Gallup. Now, 90 days and one Republican "war on women" later, Romney is trailing Obama by 14 points among those independent women and by 18 points among all female voters.

The Romney campaign is stepping up Ann's visibility to help narrow the gender gap. The campaign is also organizing "Women for Romney" grassroots groups in several battleground states and running on the message that women are more concerned about the economy than the social issues, like birth control, on which Democrats have been attacking Republicans.

The ad casting Ann as the rock-solid center of her male-dominated household strikes a contrast with Obama, the father of two daughters, who frequently talks about his upbringing in a family of females.

His story, Obama often says, "begins with the women who've shaped my life."

"I grew up the son of a single mom," Obama said most recently at a White House forum for women last week. "When my mom needed help with us, my grandmother stepped up. ... And then there is the woman who once advised me at the law firm in Chicago where we met. ... I decided to marry her."

Romney's support among female voters began to erode when Democrats started charging that Republicans were waging a war on women by supporting legislation that would limit reproductive rights and insurance coverage for contraceptives.

Republicans shot back that Democrats were lying and pandering to win women's votes.

For his part, Romney has tried to remain above the fray. When conservative radio host Rush Limbaugh called a woman who expressed public support for contraceptive coverage a "slut," Romney chose not to rebuke him. But Democrats attacked him for failing to defend women.

"Mitt Romney, all he could muster as a response to Rush Limbaugh ... was that those weren't the words he would have chosen," Democratic National Committee Chairwoman Debbie Wasserman-Shultz told Bloomberg TV. "It's clear in this country that the jury of women across America have ruled, the Republicans have been unbelievably extreme and out of touch and hyper-focused on cultural issues."

Romney will be able to narrow the gender gap by November, but history suggests he's unlikely to win a majority of female voters, said Jennifer Lawless, director of American University's Women & Politics Institute.

"In every presidential election since 1980 there's been a gender gap where women have been more likely than men to favor a Democrat," Lawless said. "There's only so much Ann Romney can do."