A Rick Santorum rally in Washington state: The social conservative's popularity among women has risen 13 percent since January, according to a new poll.

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ick Santorum's popularity with Republican women is on the rise despite his controversial positions on women's issues, including his opposition to birth control, prenatal testing, and abortion rights, according to a new Washington Post-ABC News poll. His favorability among GOP women has jumped by 13 percent since January to 57 percent, just under Mitt Romney's. Santorum is also less unpopular with Democratic and independent women than are any of his rivals for the GOP presidential nomination — Romney, Newt Gingrich, and Ron Paul. Why? Here, four theories:

1. Santorum connects better with struggling families
"Santorum doesn't just talk about family planning," says Noreen Malone at New York. He also "talks about the practice and daily problems of actually having a family," which is helping him connect to struggling, middle- and low-income voters in ways that the distant, super-wealthy Romney just can't. "Perhaps that's more important for Republican voters right now."

2. Women respect his honesty
Even GOP women who don't share Santorum's anti-abortion views — and, remember, many of them do — can respect him for being "honest about his extremist" ideas, says Taylor Marsh at her blog. Next to "Romney's impossibly inauthentic persona," Santorum's a welcome change.

3. Obama's attempt to make birth control an issue flopped
Obama was hoping to split women away from Republicans, says Ed Morrissey at Hot Air, by requiring religious organizations to provide free birth-control coverage to their employees. Santorum, who was "the most vocal about the need to protect religious liberty in the face of the mandate," would have been the big loser if the ploy had worked. Obviously, it didn't. The fact that "women are flocking to his side even after a week of the media hype over contraception" makes it clear Obama "badly miscalculated."

4. Women only prefer Santorum because they don't know him
"Women detest Newt Gingrich," says Taylor Marsh at her blog, and they find Mitt Romney "wholly untrustworthy." Santorum looks good by comparison because voters don't really know very much about him. But wait until November — if he makes it that far — when "Team Obama starts using Santorum's words against him, and voters find out just "how hostile he is to modern women." Suburban Republican women and independents will start "running for the hills."