WASHINGTON • Sitting in his pew at St. Louis Catholic Church in Miami one recent Sunday, Sen. Marco Rubio heard the same homily as other parishioners who were urged by church leaders nationwide to contact Congress about the use of contraceptives.

Well-positioned to act, the Florida Republican senator last week filed legislation that would repeal the part of the federal health care law that requires some religious institutions to offer contraceptives and family planning services without co-payments in their health coverage.

Rubio has always opposed abortion, including during his days in the Florida Legislature. In recent weeks, though, he has emerged as one of the leading national warriors in the politically explosive cultural war over what sort of health care women have access to.

His leadership on the issue is set against the backdrop of a national debate: the Susan G. Komen for the Cure breast cancer charity's decision to end — then restore after protests— grants for breast cancer detection to Planned Parenthood.

Last week alone, Rubio keynoted the annual banquet of the Susan B. Anthony List, a political organization that helps anti-abortion office-seekers get elected, and he introduced the bill that would exempt religious institutions from complying with the contraception requirement. He has previously said he would vote to defund Planned Parenthood, which receives federal money to provide health care for poor women and men. The organization provides abortion services.

Rubio has 20 Republican co-sponsors in the Senate for the bill. A version of the bill in the Republican-dominated House has a better chance of passage than in the Democratic-controlled Senate.

Rubio defended his legislation Friday in an op-ed in the New York Post.

"From a practical standpoint, this will force Catholic organizations to make an unacceptable choice: ignore a major tenet of their faith, or not provide any insurance to their employees and be punished with a federal fine for violating Obamacare's mandate on employers," Rubio wrote. "As Americans, we should all be appalled by an activist government so overbearing and so obsessed with forcing mandates on the American people that it forces such a choice on religious institutions."

The administration of President Barack Obama defends its policy, noting that it gave religious institutions an extra year to comply with the rule, which requires most policies issued after August to offer contraceptives. Individual churches that serve only a narrow population with similar beliefs also can seek exemptions, the White House notes.

The administration also takes pains to note that 28 states already require insurers to provide contraceptives. The requirements in North Carolina, New York and California are identical to the federal requirements, said White House spokesman Jay Carney. Colorado, Georgia and Wisconsin have no exemptions at all for religious groups, the White House said.

"We want to make sure that women have access to good health care, no matter where they work, and that all women who want access to contraceptives are able to get them without paying a co-pay every time they go to the pharmacy," Carney said. "It merely requires that insurance companies provide coverage for contraceptives to patients who want them, which is the recommendation of the nonpartisan Institute of Medicine."

Said Archbishop Thomas Wenski, who heads the Archdiocese of Miami. "We're being told by the U.S. government that unless we only serve a very narrow group of people that are strictly Catholic, we have to comply with something that we feel is evil."