In 12 key swing states, only 30 percent of women under age 50 support Mitt Romney, while 60 percent back President Obama.

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month ago, Mitt Romney had a two-point edge over President Obama among voters in 12 potentially crucial swing states. Now Romney has fallen dangerously behind, with 42 percent support to Obama's 51 percent, according to a USA Today/Gallup poll. The biggest factor in the shift? A sharp drop in support for Romney among women. Only 30 percent of women under 50 back Romney — down from 44 percent in mid-February — while Obama's number with that demographic jumped from just under 50 percent to more than 60 percent. What accounts for Romney's "women problem"? Here, four theories:

1. The GOP's war on contraception is killing him
Romney's women problem started in February, says Steve Kornacki at Salon, "when Republicans revolted against the Obama administration's efforts to make birth control a mandatory component of health insurance coverage." House Republicans held a "committee hearing made up entirely of male witnesses," Rush Limbaugh called Sandra Fluke a "slut," and top Republicans were reluctant to condemn him for it. It's suddenly easy for Democrats to claim the GOP is "engaged in a 'war on women,'" and Romney is paying the price.

2. Romney hasn't found the right message
If contraception is behind this, says Molly Ball at The Atlantic, why does Romney's main GOP rival, hardline social conservative Rick Santorum, do better among swing-state women than Romney? Maybe the real problem is that "Romney's economic message is leaving women cold." Mitt has been deploying his "charming wife Ann to do women's outreach; her pitch revolves around how concerned women are about the deficit." But the swing-state poll found that women's No. 1 concern is health care — the deficit is fourth. If Romney hopes to make inroads, he'll have to find a better message.

3. He just doesn't get women
When Romney needs to counter Democrats' claims that the GOP is at war with women, Romney relies on Ann to make his defense, says Amy Davidson at New Yorker. "It is a symptom of Romney's women problem that he thinks his wife might be an answer to his women problem." Apparently, Romney imagines "the electorate as a cocktail party or a company barbecue, where his wife can be relied on to talk to the spouses and then report back to him." Really, Mitt, "you don't need to be a woman to listen" to women.

4. It's a reflection of Romney's lackluster support overall
Romney was always fighting an uphill battle with women, says William McGurn in The Wall Street Journal. After all, Obama won handily among women in 2008. And yet, Romney's women problem is symptomatic of a larger issue: "His inability to generate much excitement among women appears related to a general inability to generate much excitement among anyone."