WASHINGTON — Democrats are deeply divided over President Barack Obama's new rule that religious schools and hospitals must provide insurance for free birth control to their employees amid fresh signs that the administration was scrambling for a way out.

"This is not only unacceptable, it is un-American," says Sen. Joe Manchin, D-W.Va., a Catholic who faces re-election in November in a state where Wednesday nights are reserved for church services.

Another Catholic senator, Bob Casey of Pennsylvania, has pleaded with the administration "to correct this decision which will erode the conscience rights" that have been protected for decades. His opposition echoes the criticism of his bishop in Scranton, Rev. Joseph C. Bambera.

Several Democrats, including Senate candidate Tim Kaine in Virginia and Illinois Rep. Dan Lipinski, have been outspoken in assailing the recently announced administration mandate that has angered religious groups and unified Republicans in protest. In a reflection of the party split, Senate Majority Leader Harry Reid, D-Nev., on Thursday blocked a GOP effort to debate an amendment on religious freedom.

A day earlier, liberal female senators thanked Obama for the new policy during a closed-door retreat.

"We're here to stand up for the women of America who deserve to have access to free preventive care through their health insurance," Sen. Barbara Boxer, D-Calif., said later at a news conference.

House Minority Leader Nancy Pelosi, D-Calif., on Thursday promised a fierce debate on women's rights if Republicans tried to repeal the policy.

Even though church-affiliated hospitals, colleges and social service agencies will have one additional year to comply with the requirement, issued last month in regulations under Obama's health care overhaul, the outcry has been loud and fierce. Facing intense pressure, the White House indicated this week that it is trying to come up with a compromise.

Vice President Joe Biden, a Catholic, said in a radio interview Thursday that "there is going to be a significant attempt to work this out and there is time to do that." He said the one-year grace period is "to make sure that we do not force the Catholic Church to do something that they fundamentally think is inconsistent with their religious beliefs."

He spoke with Bill Cunningham of 700 WLW in Cincinnati.

The party break over the contentious issue could reverberate in an election year, with implications not only for Obama in battleground states with significant numbers of Catholic working-class voters such as Ohio and Pennsylvania, but also for Democrats in congressional races. The political upside for Casey or Manchin is a fresh opportunity to show their independence from the president; the political downside is potentially pushing too far on a matter that resonates with female voters critical to the Democrats' prospects in November.

In a show of defiance, Manchin joined forces with Republican Sen. Marco Rubio of Florida on Thursday in introducing legislation to expand the religious exemption and undo the Obama policy.

"I don't know why the federal government jumped in at the level they did," Manchin said.

Another West Virginia Democrat, Sen. Jay Rockefeller, joined Casey and Kaine in pressing for continued access to preventive health care services for women but ensuring that religious liberties are protected. Rockefeller sent a letter to Health and Human Services Secretary Kathleen Sebelius on Thursday urging her to consider what Manchin signed into law when he was governor of West Virginia. The state is one of 28 that require health insurance plans to cover birth control. However, not all have the same exemptions for church-affiliated employers.

Manchin has been in touch with his bishop, Rev. Michael Bransfield, of the diocese for Wheeling and Charleston, who has called the rule "a radical break with the tradition of religious liberty and respect for conscience rights."

More than 150 Catholic cardinals and bishops throughout the country have been relentless in assailing the policy, with many of their letters on the policy sent to parishioners or read aloud at Sunday Masses.