The House will cast a landmark vote Thursday when it decides whether to reverse U.S. policy and provide contraceptive grants to groups overseas that also provide abortions.

The legislation states the U.S. cannot deny grants to any group so long as the assistance includes funding for contraceptives. President Bush has threatened to veto the measure, and Republicans say they have enough support to uphold the veto.

"I'm seriously concerned about the ramifications that such a policy change would have on our ability to respect the innocence of human life and human rights worldwide," said Rep. Ileana Ros-Lehtinen of Florida, the top Republican on the House Foreign Affairs Committee.

Both sides consider the vote to be a crucial step in the abortion debate. U.S. policy, initiated by President Reagan and reinstated by President Bush in March 2001, bars any assistance to organizations abroad that perform or promote abortion as a method of family planning.

Democrats have since contended the policy does nothing to prevent the unwanted pregnancies that lead to abortion. Accordingly, Democrats drafted a provision they said would allow U.S. donations of contraceptives, but no money to any organization, regardless of its position on abortion.

The bill would help "reduce unintended and high-risk pregnancies, and abortions . . . and save the lives of mothers," said Rep. Nita Lowey, who chairs the House appropriations panel that oversees the foreign aid budget.

"This provision does not amend any of the provisions in existing law that prohibit assistance for abortion or otherwise restrict family planning funds," Lowey later added.

Despite Lowey's description, the bill is not written that way.

"No contract or grant which includes funding for the provision of contraceptives in developing countries, shall be denied to any non-governmental organization solely on the basis of" Bush's 2001 policy, the bill states.

The measure is attached to a $34.2 billion bill that pays for State Department operations and foreign aid in 2008.

"This clearly opens up the U.S. Treasury to fund abortions worldwide," said Rep. Mike Pence of Indiana, a senior Republican on the House Foreign Affairs Committee.

The proposal ignited a firestorm of angry protests from conservative GOP congresswomen, who said they would back an amendment to strip the measure from the funding bill.

"It makes sense that if we do not use U.S. taxpayer funds to fund abortions in the United States, we should not use taxpayer dollars to export this procedure to other countries," said Rep. Jean Schmidt, R-Ohio. "Congress should not ... be entering into the position as being seen exporting abortion all over the world."

Said Rep. Marilyn Musgrave, R-Colo: "As a nation we must not export this abortion policy. "

Democrats and supporters of their proposal say the new law would not promote abortion, but correct a shortage in contraceptives available in poor rural areas. According to Population Action International, Ghana has shown increased rates of sexually transmitted infections and abortions since a prominent family planning group in the country was denied U.S. assistance.

Bush policy "has had a destabilizing impact on country-led family planning programs and simultaneously undermined decades of health care provision by leading national" non-governmental organizations, the group states.

Pence said late Wednesday Republicans were unsure they had enough votes to pass an amendment overturning the Democratic proposal. But he said, the GOP was sure Democrats lacked the votes to override a presidential veto.

In a statement released Tuesday, the administration said the president would veto any legislation "that weakens current federal policies and laws on abortion."