Catholic bishops and Protestant evangelists in the US have unleashed an intense lobbying campaign to force fresh limitations on access to abortion into healthcare legislation under debate in the Senate this week.
Pro-choice groups have described the religious ambush of health reform - which this month pressured the House of Representatives to effectively block women from using medical insurance to pay for abortions - as one of the most serious threats to abortion rights of recent years.
The campaign has thrust the divisive issue back to the forefront of US politics, pitting the White House and its allies against religious leaders who have accused the Obama administration of being part of a "culture of death".
Ten days ago more than 150 bishops and other religious leaders issued a declaration denouncing Barack Obama's position on abortion and threatening civil disobedience against new laws affecting that and other social issues, such as gay marriage.
Anti-abortion activists were reinvigorated ahead of the opening of the healthcare legislation debate in the Senate today by their success in garnering support in the House of Representatives over an issue that was widely regarded as having lost its political potency with the election of a pro-choice president.
At the core of the strategy by the Catholic church and Christian evangelists is a campaign to rally churchgoing voters to pressure members of Congress to ensure that new healthcare laws bar government funds from paying for abortions.
The measure's supporters say it merely extends existing policy. But Naral Pro-Choice America, one of the country's largest abortion rights groups, says the effect of such legislation will be to prevent insurance companies that presently pay for abortions from covering terminations. This, they say, is because government funds will be used to run a new insurance exchange designed to make the market more competitive and to subsidise coverage for low-income families.
Naral's communications director, Ted Miller, called the inclusion of the amendment "a wake-up call for America's pro-choice majority".
"It's clear that the election of a pro-choice president and the perception of a pro-choice majority in Congress led many Americans to believe that they could be complacent about a woman's right to choose," he said.
"It goes far beyond the status quo. The amendment would make it nearly impossible for private insurance plans to cover abortion. The status quo is that about 85% of private insurance plans currently cover abortion services. It really prevents women from being able to use their own money to purchase an insurance plan that includes abortion coverage. That's far, far out of step with the current private insurance market."
Pro-choice advocates had thought the anti-abortion camp was in retreat after recent political gains, including Obama's election victory and seven failed attempts to curb abortion rights by public ballot in four states since 2005. Opinion polls showed younger voters were less passionate about the issue than their elders.
But there were flickerings of the old fire when abortion emerged as a central issue in a New York state congressional race last month. Sarah Palin joined other prominent rightwingers in rejecting the Republican candidate, Dede Scozzafava, because she was pro-choice and supported same-sex marriage. They threw their weight behind a hard right independent candidate who eventually lost to a Democrat after Scozzafava withdrew from the race.
On Friday more than 150 Christian leaders and activists, led by conservative evangelicals and Catholics, issued a long declaration denouncing abortion, along with gay marriage and liberal social policies, and threatening to break laws that compromised their beliefs.
The Manhattan Declaration: A Call of Christian Conscience says that Obama's stated aim of reducing the need for abortion is a "commendable goal" but alleges that his policies will increase the number of terminations, while accusing the government of being part of "a culture of death".
"The present administration is led and staffed by those who want to make abortions legal at any stage of foetal development and who want to provide abortions at taxpayer expense," the declaration reads. "Majorities in both houses of Congress hold pro-abortion views."
Among the signatories are 15 Catholic bishops and leading evangelical Christians such as James Dobson, the founder of Focus on the Family.
The declaration says supporters will be "united and untiring in our efforts to roll back the licence to kill that began with the abandonment of the unborn to abortion". Measures will include defiance of the law if laws protecting individuals from having to act against their conscience are changed: for example, if religiously affiliated hospitals are obliged to assist in abortions or research involving the destruction of embryos.
"Through the centuries Christianity has taught that civil disobedience is not only permitted, but sometimes required," the declaration says.
"We will fully and ungrudgingly render to Caesar what is Caesar's.
But under no circumstances will we render to Caesar what is God's."
While a resurgent opposition to abortion has brought various religious interests together, they are otherwise sharply divided about the broader healthcare legislation. Catholic leaders strongly favour ensuring that undocumented immigrants are covered, and a recent opinion poll of Catholic voters showed 73% in favour of a government-run health insurance plan. The evangelical right is passionately against both measures.