WASHINGTON (Reuters) - The U.S. Supreme Court on Wednesday appeared to be headed toward a possible 4-4 split over a legal challenge launched by Christian groups demanding full exemption on religious grounds from a requirement under President Barack Obama's healthcare law to provide health insurance covering contraceptives.

Justice Anthony Kennedy, who often casts the deciding vote in close cases, appeared more aligned with the court’s three other conservatives in favoring the Christian groups. The court’s four liberals appeared likely to side with the Obama administration. Only eight justices are considering the case following the death of conservative Justice Antonin Scalia in February.

The court heard a 90-minute oral argument on seven related cases focusing on whether nonprofit entities that oppose the requirement for religious reasons can object under a 1993 U.S. law called the federal Religious Freedom Restoration Act to a compromise measure offered by the government.

A 4-4 split would leave in place lower court rulings that rejected the challenges mounted by the Christian groups but would set no national legal precedent.

(Reporting by Lawrence Hurley; Editing by Will Dunham)