Washington ? The Bush administration is asking the Supreme Court to reinstate a national ban on a type of late-term abortion, a case that could thrust the president’s first court picks into an early tie-breaking role on a divisive and emotional issue.

The appeal follows a two-year, cross-country legal fight over the law and highlights the power that Bush’s nominees will have. Just a few months ago, there would have been five votes to strike down the law, which bars what critics call partial-birth abortion.

The outcome is now uncertain, with moderate Justice Sandra Day O’Connor retiring and her replacement still unnamed.

“This no longer puts the abortion issue in the abstract with the Supreme Court. This is as live a controversy as you can get,” Jay Sekulow, chief counsel of the conservative American Center for Law and Justice, said Monday.

Abortion was already expected to be a major subject in the next round of confirmation hearings, just as it was with the hearings of John Roberts to be chief justice. The Senate began debating Roberts’ nomination on Monday, with confirmation expected later this week.

President Bush had supported the 2003 law outlawing what he termed an “abhorrent practice.” President Clinton twice vetoed similar bills, arguing that they lacked an exception to protect the health of the mother, something the Supreme Court has said is required in abortion laws.

The law Bush signed was challenged even before it took effect and has never been enforced. Challengers won rulings in New York, California and Nebraska that the law was unconstitutional because of the lack of a health exception.

The Supreme Court is already dealing with a similar issue, in a test of New Hampshire’s parental notification statute. That case turns on whether the state law is unconstitutional because it lacks an exception allowing a minor to have an abortion to protect her health in the event of a medical emergency.

The court should review both cases, Solicitor General Paul Clement said in the appeal, filed Friday and released Monday.

The federal Partial-Birth Abortion Ban Act prohibits a type of abortion, generally carried out in the second or third trimester, in which a fetus is partially delivered before being killed.

The earliest that justices could hear arguments on the law is next spring. By then, the court should have two new members.