Mitt Romney and his running mate Paul Ryan were scrambling on Wednesday to present a coherent position on abortion amid accusations from Democrats that the Republican presidential candidate had hidden his true beliefs in an attempt to appeal to moderate voters.

In the wake of a Romney interview with the Des Moines Register newspaper in which he said his agenda included no legislation to restrict abortion, his campaign team launched a damage limitation exercise to assure conservative voters that he remained staunchly pro-life.

Within hours of the comments being published on Tuesday, Romney's campaign insisted that he was against abortion, telling the conservative National Review Online that Romney "would, of course, support legislation aimed at providing greater protections for life.

"Mitt Romney is proudly pro-life, and he will be a pro-life president," said his spokeswoman Andrea Saul in a statement.

But on Wednesday, an intervention by Ryan during a campaign stop deepened the confusion. Asked by reporters about the differences between him and Romney on the issue, Ryan, who is against abortion in all cases, including rape, incest and where the mother's life is in danger, said: "Our position is unified. Our position is consistent and hasn't changed."

As the controversy escalated, Romney himself sought to draw a line under it.

He told reporters in Ohio: "I think I've said time and again that I'm a pro-life candidate and I'll be a pro-life president. The actions I'll take immediately is to remove funding for Planned Parenthood. It will not be part of my budget. And also I've indicated that I will reverse the Mexico City position of the president. I will reinstate the Mexico City policy which keeps us from using foreign aid for abortions overseas."

Romney's anti-abortion views are less extreme than Ryan's. While he has stated that he supports the overturning of the Roe v Wade supreme court decision, he believes there should be exceptions to a ban on abortion.

Ryan, by contrast, has sponsored a series of bills that would either restrict abortion or access to contraception, or both. The differing views of the two men over the issue was highlighted most recently in August when Ryan's views were tied to those of Todd Akin, the Republican Senate candidate in Missouri who was abandoned by the party after comments on "legitimate rape".

Two months ago, when asked a similar question about the difference on abortion between him and Romney, Ryan acknowledged the difference between them when he told reporters he was "proud of my pro-life record" but said that Romney set the policy.

A call to the Romney campaign from the Guardian to clarify the position – and what Ryan's "unified" comment meant – was not immediately returned.

Romney's initial remarks to the Des Moines Register were pounced on by Barack Obama campaign officials, who accused him of "cynically and dishonestly" hiding his true anti-abortion position.

Stephanie Cutter, Obama's deputy campaign press secretary, told reporters: "We're not saying that he's changed his mind on these issues. We're saying that he is trying to cover up his beliefs."

She added: "Every step of the way he has been anti-choice, against Roe v Wade."

Reaction among conservatives to Romney's remarks was also critical. A comment piece in the conservative newspaper The Weekly Standard on Wednesday titled "Did Mitt Romney forget?" suggested that he was "mistaken" and had simply not realised how many issues related to abortion funding he could influence.

"The issue here does not appear to be that Romney is backing off his stance on abortion – indeed, he says he will use an executive order to cut off funding to groups that perform abortion overseas," it read. "But he is mistaken in thinking that there aren't issues related to abortion funding are handled through the legislative process at the federal level."

Romney's past commitments have included ensuring US laws reflect "values of preserving life". He has previously promised to: support foetal pain legislation, which bans abortion after 20 weeks, on the much-debated basis that foetuses can feel pain at that stage; end public health funds for Planned Parenthood because the group provides abortions; and support a decades-old ban on federal funds for abortions.

He supports the reversal of Roe v Wade, but believes in exceptions for victims of rape and incest, or when the mother's life is in danger.

Romney, who had been pro-choice as governor of Massachusetts, repeatedly asserted his anti-abortion credentials as he battled to win the Republican nomination. During a televised debate in Charleston on 19 January before the South Carolina primary, for example, he said: "You can count on me as president of the United States to pursue a policy that protects the life of the unborn, whether here in this country or overseas. And I'll reverse the policies of this president."

In his acceptance speech to the Republican convention in Tampa in August, he promised that as president he would "protect the sanctity of life".

Anti-abortion groups said on Wednesday they didn't see Romney's comments as evidence of a change of heart. Tony Perkins, president of the anti-abortion Family Research Council, told Talking Points Memo the Romney campaign called him soon after the remarks were published by the Iowa newspaper and assured him it didn't represent a shift from his support for pro-life issues.

Romney's comments came as he sought to maintain his recent appeal to female voters in the closing stages of the presidential race. A poll by Pew this week found Romney neck-and-neck among women with Barack Obama, who has held an enormous advantage with this demographic.