President Obama on Thursday defended his administration’s decision to block unrestricted sales of the morning-after pill as a “common-sense” parenting choice, even as women’s rights advocates condemned it as a cynical move that could provoke a damaging political backlash for the president next year.

The administration, according to several Democratic allies, took a calculated risk in making the decision to overrule the Food and Drug Administration, which had concluded that the contraceptive should be made available to people of all ages directly off drugstore and supermarket shelves without a prescription.

Although the decision, announced Wednesday by Health and Human Services Secretary Kathleen Sebelius, angered women’s groups, some of the president’s allies said that allowing the FDA ruling to stand could potentially have been more politically damaging for Obama if he was portrayed as giving teenage girls unfettered access to the morning-after pill.

Obama, appearing in a briefing room at the White House, said he was not involved in the decision to require a prescription for girls 16 and younger before it was announced, leaving it up to Sebelius.

But, he added: “As the father of two daughters, I think it is important for us to make sure that we apply some common sense to various rules when it comes to over-the-counter medicine.”

“And as I understand it, the reason Kathleen made this decision was she could not be confident that a 10-year-old or an 11-year-old, going to a drugstore, should be able, alongside bubble gum or batteries, be able to buy a medication that potentially if not used properly could end up having an adverse effect,” Obama said. “And I think most parents would probably feel the same way.”

Asked whether he supported the decision, Obama offered a definitive “I do.”

Meanwhile, the political reverberations continued Thursday.

“The political calculations that the administration is making around this are disheartening,” Jessica Arons of the liberal think tank Center for American Progress said. “They seem to be very concerned with conservative, religious voters, and are trying to maintain what margins they can with that audience. But it’s missing the forest for the trees.”

Sen. Patty Murray (D-Wash.) called on Sebelius to explain the scientific underpinnings of her decision. “I want to know what the scientific evidence is that the secretary made this decision on in overriding the FDA,” Murray said. “Pharmaceutical companies here in this country make some very expensive decisions, and they need to know that the FDA is going to base a decision based on science.”

One former White House official familiar with decision-making on such issues said the scientific evidence clearly supported the FDA’s findings that it was safe for girls younger than 17 to use Plan B without a prescription — adding that this was a higher standard than that applied to any number of potentially lethal medications offered over the counter.

“One of the president’s first executive orders was that we will use science to guide decisions and not politics,” said the official. “And I don’t understand how this can possibly square with science.”

The official also said that conversations with people knowledgeable about the move had left the clear impression that, in keeping with usual practice, the Plan B decision was made not by Sebelius but by White House officials who consulted political advisers “to get the macro politics right.”

A senior Democratic Senate staffer said women’s advocates were also convinced of the White House’s political involvement given Sebelius’s record of supporting abortion rights while governor of Kansas.

“Kathleen Sebelius has been a hero to the pro-choice community,” said the staffer. “So I think it’s going to be hard to convince this community that she was the one who pushed this without any input from the political folks at the White House.”

Heading into the 2012 presidential campaign, Obama faces competing political crosswinds connected to reproductive rights. While he needs to ensure that pro-choice women skew Democratic as they usually do in presidential elections, Obama must also win a certain percentage of religious voters, including Catholics. Obama enjoys an edge among female voters over the Republican hopefuls, especially former House speaker Newt Gingrich.

Some advocates on women’s issues said the president risks losing that base of support if he is perceived as curtailing access to contraceptives. Wednesday’s decision means that even adults will continue to be required to ask pharmacists for the medication — which will continue to be kept behind the counter — and show proof of age.

How the issue will play politically in the country at large is a complex matter.

“There is a damned if you do, damned if you don’t quality of this one. The political benefits and drawbacks aren’t that clear cut,” said Democratic pollster Geoff Garin, who has worked for Planned Parenthood. “It seems completely plausible that at the end of the day, this was about the public policy considerations, not just the political considerations.”

Women are generally supportive of contraceptive rights, but it could become more complicated when the question involves contraceptives for girls as young as 11. Although Plan B works primarily by preventing eggs from being released and fertilized, opponents also focus on the possibility that the drug could prevent an early embryo from implanting in the uterus, and they consider that equivalent to an abortion.

Even Obama aides said the decision appeared to be rooted less in science than in a gut feeling that teenagers might not be ready to make decisions about pregnancy. “This was really Sebelius raising red flags, saying, ‘Do we really want to put ourselves on record saying this makes sense?’ ” one Obama adviser said.

But Democratic pollster Celinda Lake said she could “not even remotely” understand the political calculus of the decision, saying it “alienates the base, causes conflict with women in the base, [is] bad for key groups of women like younger women and unmarried women, and doesn’t win the swing independent women.”

Polling analyst Scott Clement contributed to this report.