WASHINGTON — Abortion opponents are raising questions about a critical new insurance program under President Barack Obama's health care overhaul law.

Federal officials say elective abortion is barred under the Pre-Existing Condition Insurance Plan. It offers coverage to people turned down by private insurers because of medical problems, at rates comparable to what the healthy pay.

But at least one state — New Mexico — initially listed elective abortion as a covered benefit, reversing course after The Associated Press inquired on Wednesday.

National Right to Life and other abortion opponents say rules for the program have not been clearly spelled out, and that could open the way for taxpayer-subsidized coverage of elective abortion. Federal law bars paying for abortion with government money, except in cases of rape or incest or to save the mother's life.

"We don't think this is just a problem of vagueness, we see a pattern of the Obama administration trying to expand abortion any time they can get away with it," said Douglas Johnson, legislative director for National Right to Life.

A spokeswoman for the federal Health and Human Services Department said that's totally wrong, and insisted there was no intention of allowing abortion coverage under the new program, also known as PCIP.

"In all our PCIP plans, abortions will not be covered except in the cases of rape, incest or where the life of the mother would be endangered," said Jenny Backus. The department is working on guidance to make those restrictions explicit to states and insurance plans.

Abortion coverage was one of the most difficult issues in last year's epic congressional debate over health care. Democrats were able to muster enough votes to pass the bill in the House only after Obama agreed to sign an executive order affirming longstanding restrictions on taxpayer-funded abortions.

The health overhaul law attempted to strike a compromise. Private plans in new insurance markets opening for business in 2014 can cover abortion, but payment must come from enrollees themselves, not from federal tax credits that will be offered to make premiums more affordable.

However, lawmakers left it to bureaucrats at HHS to write the rules for pre-existing conditions coverage, a $5 billion program entirely subsidized by federal taxpayers. It's intended to serve as a stopgap until 2014, when insurers will no longer be able to deny coverage to people with medical problems.

Twenty-nine states and Washington, D.C., are administering their own plans. The federal government is running the program in the remaining 21 states.

Michelle Lujan Grisham, deputy director of the New Mexico Medical Insurance Pool, said the state's contract with HHS stipulated that the plan must follow federal law, but there was no clear-cut mention of abortion coverage.

As a result, New Mexico included elective abortion as a covered benefit, following what it was already doing with its own state health programs.