WASHINGTON (RNS) Congressional leaders and Republican presidential candidates joined Catholic religious groups on Wednesday in denouncing the Obama administration's mandate requiring health insurers to offer birth control coverage, but the White House stood its ground.

House Speaker John Boehner called it “an unambiguous attack on religious freedom” in a rare House floor speech decrying the mandate, a part of President Obama's health care law that has picked up Roman Catholic and conservative opposition in the past three weeks.

“If the president does not reverse the … attack on religious freedom, then the Congress, acting on behalf of the American people and the Constitution we are sworn to uphold and defend, must,” Boehner said. “This attack by the federal government on religious freedom in our country must not stand and will not stand.”

The issue has heated up since Jan. 20, when Secretary of Health and Human Services Kathleen Sebelius issued a final rule requiring that all women have access to free preventive care services, including contraceptives. The rule includes an exemption for churches and houses of worship, but not for other religious institutions such as hospitals, universities and charities.

Republican leaders have been joined by a few Democrats — such as Sens. Robert Casey of Pennsylvania and Joe Manchin of West Virginia and House Democratic Caucus Chairman John Larson of Connecticut — in calling for changes in the policy.

Faced with growing criticism, the White House indicated a willingness to review the issue but insisted that women be allowed free access to birth control. One possible solution could be to make contraceptive coverage available to employees of religious institutions without their employers' direct involvement.

“We are very sensitive and understand some of the concerns that have been expressed,” White House press secretary Jay Carney said. “The president takes those concerns very seriously.”

Carney said Obama remains “very aware of and engaged in this issue” as the administration seeks to allay the concerns expressed by religious institutions. “We're not trying to win an argument here,” he said. “We're trying to implement a policy that will affect millions of women.”

On the campaign trail, former Pennsylvania senator Rick Santorum said the policy, which he blistered in his victory speech Tuesday night, had not been a major factor in his sweep of contests in Colorado, Minnesota and Missouri. He has based much of his campaign on social issues such as abortion and gay marriage.

“When government gives you rights, the government can tell you how to exercise those rights,” Santorum said during his victory speech in St. Charles, Mo. “And we saw that just in the last week, with a group of people, a small group of people — just Catholics in the United States of America! — who were told you have a right to health care, but you will have the health care that we tell you you have to give your people, whether it is against the teachings of your church or not.”

Mitt Romney, who until Tuesday was the prohibitive front-runner for the nomination, found himself on the defensive after Carney said the former governor had presided over a “virtually identical” policy in Massachusetts. “That was a provision that got there before I did, and it was one that I fought to remove,” Romney said.

The White House has pointed to 28 states with similar laws, including eight without the religious exemption contained in the federal rule, as proof that requiring free access to contraceptives is workable.

The rule goes into effect Aug. 1, but if objections are raised, another year's extension is possible.

That was no consolation to Catholic leaders. The White House is “all talk, no action” on moving toward compromise, said Anthony Picarello, general counsel for the U.S. Conference of Catholic Bishops. “There has been a lot of talk in the last couple days about compromise, but it sounds to us like a way to turn down the heat, to placate people without doing anything in particular,” Picarello said. “We're not going to do anything until this is fixed.”

That means removing the provision from the health care law altogether, he said, not simply changing it for Catholic employers and their insurers. He cited the problem that would create for “good Catholic business people who can't in good conscience cooperate with this.”

“If I quit this job and opened a Taco Bell, I'd be covered by the mandate,” Picarello said.

Senate Democrats who met with Obama on Wednesday came away convinced he would not back down on requiring some form of access for all women, regardless of where they work.

“We support the right of women in this country to haveaccess to birth control through their insurance policies, and anybody who stands in the way is going to have to deal with us and our friends,” said Sen. Barbara Boxer, D-Calif., flanked by four colleagues. Boxer said she had spoken to Obama adviser David Axelrod, who assured her that the administration would not weaken its position.

More than 600 physicians and medical students from 49 states signed a letter to Obama and Sebelius, urging them to stand firm in defense of the rule. They said millions of women rely on birth control pills for othermedical conditions.

Roman Catholic leaders showed no sign of backing down,either.

“There's no room for compromise on this. The mandate has to go,” said John Allen, senior correspondent for the National Catholic Reporter and author of numerous books on the Catholic church. “There's not much room for a conversation here.”

(Richard Wolf and Cathy Lynn Grossman write for USA Today. Susan Davis of USA Today contributed to this report.)