By Steve Schifferes BBC News Online in Washington

The Supreme Court is the focus of protests

It is the culmination of an eight-year struggle between supporters and opponents of abortion who are playing for high political stakes.

The Republicans, lead by majority leader Bill First, want to pass the ban on what they say are "brutal, savage late term abortions".

The bill says that "partial birth abortion is never necessary to preserve the health of a woman, poses serious risks to a woman's health and lies outside the standard of care".

The Congress passed a ban twice before, only to see it vetoed by former President Bill Clinton.

In his state of the union address, however, President Bush called for such a ban.

But the Supreme Court has struck down a similar state law which banned partial birth abortions.

Fears

But pro-choice leaders charge that it is part or a broader campaign to limit women's rights.

"It is important for the American public to understand that President Bush and the Congress have taken aim at a woman's right to choose and they are relentless in their assault on reproductive rights," said Kate Michelman, head of Naral Pro-Choice America.

ABORTION IN THE US Abortion legalised by Supreme Court in landmark Roe v Wade case in 1973 1.3 million abortions in 2000, down from 1.6 million in 1990 21.3 abortions per 1,000 women nationwide Number of providers fell from 2,042 in 1996 to 1,819 in 2000 33 states limit abortions for minors

There are around 2,000 late term abortions performed in the US each year, a small fraction of the total number of abortions.

But those numbers have been falling in recent years, with the wider availability of "morning after" pills and the decline in the number of abortion clinics.

Last week the Supreme Court ruled that anti-abortionists who picket those clinics are not liable to prosecution under anti-racketeering laws.

Supreme Court

The abortion issue has also been closely fought on the Supreme Court, which first legalised abortion in l973.

In a 5-4 ruling in 2000 that struck down a Nebraska partial birth abortion statute, the Supreme Court said that law was vaguely worded and created an undue burden on a woman's right to choose an abortion.

The court also ruled that the state law was deficient because it failed to provide an exemption for the health of the mother.

The new Congressional bill does provide this exemption, however.

Opponents of abortion are hoping that President Bush will be able to appoint an anti-abortion judge to the Supreme Coourt when a vacancy arises.

Part of the reason for another bitter battle in the Senate, over the nomination of the conservative Miguel Estrada to be an appeals court judge, relates to Democratic fears that he would be a strong candidate to fill that Supreme Court seat.