But Romney has seized on the issue, arguing that the president's regulations are an attack on "religious liberty." On Monday, his campaign began circulating an online petition against the regulation.

"The Obama administration is at it again. They are now using Obamacare to impose a secular vision on Americans who believe that they should not have their religious freedom taken away. ... If you have had enough of the Obama administration's attacks on religious liberty, stand with Mitt and sign the petition," the petition reads.

That has Romney's political opponents calling the former governor a hypocrite.

Newt Gingrich told a crowd at a restaurant in Ohio that Romney was no better on the issue than the president.

“RomneyCare and ObamaCare they're too similar,” Gingrich said. “There's been a lot of talk about the Obama administration's attack on the Catholic Church. Well the fact is, Gov. Romney insisted that Catholic hospitals give out abortion pills against their religious belief when he was governor.”

Romney was also quoted saying in the Boston Globe that he believed in his "heart of hearts" that rape victims should have access to the morning-after pill. It's those comments that Rick Santorum seized upon Tuesday in an op-ed piece.

"This is not the first time that elected officials have trounced on the fundamental right to religious freedom. In December 2005, Governor Mitt Romney required all Massachusetts hospitals, including Catholic ones, to provide emergency contraception to rape victims," Santorum wrote. "He said then that he believed 'in his heart of hearts' that receiving these contraceptives — free of charge — trumped employees' religious consciences. Now, a few years later and running for president, his heart is strategically aligned with religious voters opposing this federal mandate.

The president's team has also adopted the critique of Romney's Massachusetts record in defending the bill.

"Hope petition signers don't find out Mitts MA policies are identical," tweeted deputy campaign manager Stephanie Cutter on Monday.

Obama adviser David Axelrod admonished Romney for using the issue as a "political football" during an interview on MSNBC Tuesday.

"It's particularly ironic, of course, given the fact that he governed a state where there was such a policy, similar to the one we have, had nothing to say where he passed healthcare plan that required contraceptive care similar to what we're doing," Axelrod said. "He's going to have to ultimately answer for his own policies if he's going to blow this up in this way."

Romney's campaign said the criticism was unfair considering that Romney vetoed the decision as governor, and called the criticism "desperation" on the part of his GOP opponents.

"On his first day in office, Mitt Romney will eliminate the Obama administration rule that compels religious institutions to violate the tenets of their own faith. We expect these attacks from President Obama and his liberal friends. But from Newt Gingrich and Rick Santorum, it’s a clear indication of desperation from their campaigns," said Romney spokeswoman Andrea Saul in a statement.

Alicia M. Cohn contributed to the reporting of this article.