Washington Bureau - KIM GEIGER Reporting from Washington

In a last-minute compromise to build a majority in the House, Democratic leaders agreed to new language on abortion that advocates offerers stronger guarantees that federal money will not be used for abortion and say critics say goes beyond upholding current law.

A longtime ban on federal funding of abortions has so far applied mostly to patients on Medicaid and to workers who receive health benefits through the federal government. Insurance policies sold to others have been free to offer abortion coverage and many do.

The present ban contains exceptions for rape and incest or when the life of the mother is at stake.

The battle in the House focused on what rules would apply under the broad heathcare overhaul.

A key component of the bills pending in Congress would provide federal subsidies to low- and middle-income Americans to help them buy insurance policies that meet minimum benefits standards set by the government. Millions of people would qualify for the subsidies, which would pay a significant portion of the premium.

In an effort not to prevent plans available for subsidies from offering abortion coverage, Speaker Nancy Pelosi, D- San Francisco, had included in the House Democrats' bill a complicated formula to separate federal subsidies from private dollars – requiring plans to use only private funds to reimburse providers for abortion services.

Anti-abortion advocates rejected Pelosi's approach, arguing that covering abortions through policies that are subsidized by the government would violate current law.

A new amendment, offered Saturday by Rep. Bart Stupak, D-Mich., as the House neared a final vote on the bill, would effectively ban abortion coverage by all plans that are bought using taxpayer dollars. Abortions could be covered only under the exceptions that exist in current law.

Including the Stupak provision won Democrats strong support from the U.S> Conference of Catholic Bishops, which urged Catholics to "lend their full-throated support" to the Democrats' healthcare bill.

"The bishops' stamp of approval means that this bill is unambiguously pro-life and we will vigorously oppose those who suggest otherwise," the conference said in a statement.

Rep. Keith Ellison, a liberal member from Minneapolis, was prepared to vote for the health reform package even if it included some unsettling language -- like the abortion provision that some anti-abortion Democrats and Republicans wanted to include. "I am pro-choice," he said. "But I don't believe this language will really change the status quo. Overall we are passing historic, progressive legislation that will provide important advances in women's health care, the care of newborns and children."

The amendment would not prevent insurers from covering abortion services for policyholders who pay their entire premiums without government assistance.

But abortion rights advocates say the result would be a "de facto ban" on insurance companies offering abortion services in all plans sold under the new insurance exchanges that would be created to help those without job-based coverage find policies. That's because many of the customers using the exchange would be getting subsidies.