Just when it seemed the wrenching national debate over abortion might take a back seat to a legion of pressing domestic issues, it has reemerged as a threat to President Clinton's plan to overhaul the health care system.

Clinton, who campaigned on an unabashed abortion rights platform, plans to include coverage for abortions in the standard benefits package available to everyone under his comprehensive proposal, according to sources. Most private insurance policies currently include abortion services, and the president said in Chicago last week that to exclude abortion would amount to a reduction in benefits for most insured working women.

Clinton also has asked Congress not to reimpose the Hyde amendment prohibiting federally funded abortions, such as Medicaid-funded abortions for poor women. The administration has said it plans to fold Medicaid into its new health system.

Abortion is at best a peripheral component of Clinton's national health proposal, whose major goal is to guarantee affordable, lasting coverage to all Americans regardless of their health and to tame the cost of health care, which makes up 14 percent of the gross domestic product.

But the issue has the administration in a "panic," several officials said, because there is no obvious way to sidestep the acrimonious attention abortion will receive. The administration strategy is to remind the public that comprehensive health care overhaul should not hinge on one element.

"The president and the {health care} task force want to discuss all {of the package} at once, and not piece by piece," said Robert Boorstin, task force spokesman.

It also is likely, sources said, that the plan will include a "conscience clause" that would allow institutions and medical professionals morally opposed to abortion not to perform them. This would mean if a certain HMO, for example, chose not to perform abortions it would have to contract with a facility that does perform them without additional cost to the HMO's female patients.

White House officials yesterday held open the possibility that Clinton would further delay presenting his plan -- originally to be finished in early May -- until July, following passage of the budget reconciliation bill.

Already the abortion rights and antiabortion forces are mounting aggressive campaigns in Congress, and even longtime proponents of national health care revisions are concerned that the issue could derail the larger package.

"Abortion is an issue that runs so deeply in American society, on both sides, that it, in and of itself, could be the issue that stops health reform in its tracks," said Bill Cox, chief lobbyist of the Catholic Health Association, which runs 600 hospitals and 300 long-term care facilities and opposes including abortion in the package.

In the last week, there have been signs of increased pressure from both sides of the issue.

Pennsylvania Gov. Robert P. Casey (D) said in a speech here that Clinton's health package would be "dead on arrival" if it provides coverage for abortion.

In a letter sent to task force chairwoman Hillary Rodham Clinton last Friday and released to the public, 31 female House members insisted that abortion be included in any proposal. Rep. Nita Lowey (D-N.Y.), a signer, said, "This letter serves notice to those seeking to intimidate the administration into abandoning its commitment to real choice. We will fight you every step of the way."

Also last week, the nation's Roman Catholic archbishops met in Chicago to discuss how best to oppose abortion without scuttling the larger goal of reform.

The U.S. Catholic Conference last month sent Hillary Clinton a letter supporting reform but making their opposition to abortion coverage clear.

"We believe it would be a moral tragedy, a serious policy misjudgment and a major political mistake to burden health care reform with abortion coverage," wrote the Most Reverend John H. Ricard, chairman of the conference's Domestic Policy Committee and the auxiliary bishop of Baltimore.

In a subsequent meeting with Catholic leaders in late April, Hillary Clinton said she believes the president intended to include abortion as part of a basic package of health benefits that all Americans would be able to purchase from local health plans, according to sources.

The administration may need the Catholic community to campaign for health care revisions. The Catholic church sponsors the country's largest network of nonprofit hospital and nursing homes, which together serve close to 50 million people, many of them indigent. Their own health proposal approximates the broad outline of Clinton's plan and their grassroots network is invaluable to an administration that expects to confront a plethora of special interests seeking to water down or reshape its plan.

Democratic National Committee Chairman David Wilhelm reiterated the party's support of federal funding for abortions on NBC's "Meet the Press" Sunday, and he reached out to opponents, particularly Catholics.

"I would say to those who are Catholics in our party, that people should be free to advocate the choice of life, that we ought to find these common grounds to do all that we can to make abortions rare," he said.

Catholics are not the only potential allies-turned-adversaries. In fact, no matter how the plan addresses abortion, it will not satisfy everyone.

Currently, most private insurance policies cover abortion; therefore, removing it from the basic benefit package would be likely to anger working women who have access to the services through their employer-provided policies. An employer or employee would have to purchase some type of supplementary coverage to retain the coverage.

It would be unacceptable to abortion rights groups, which supported Clinton's candidacy, to allow private insurance to pay for abortion but deny that same benefit to poor women on Medicaid.

"We don't want the government deciding which women can have abortions and which women can't," said Kate Michelman, director of the National Abortion Rights Action League.

Even Democratic members of Congress are split on where their colleagues are on the issue.

Supporters, like Rep. Patricia Schroeder (D-Colo.), said the time has never been better to secure abortion rights for women. "The new members are much stronger on the choice issue," she said.

But opponents believe including abortion coverage will alienate conservative Democrats needed to pass the overall plan.

"The president will make a bad mistake" if he includes abortion in the package, said Rep. Jim Slattery (D-Kan.). "The last thing the president needs is for people willing to support health care reform to go ballistic over abortion," he said, referring as examples to "the Catholic Church and middle- and low-income people, the Reagan Democrats."