WASHINGTON (Reuters) - Christian groups asking the U.S. Supreme Court to exempt them from the requirement to provide insurance covering contraception under President Barack Obama’s healthcare law face an uphill battle following Justice Antonin Scalia’s death last month.

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The remaining eight justices will consider seven related cases on whether nonprofit groups that oppose the requirement on religious grounds can object under a U.S. law called the Religious Freedom Restoration Act to a compromise version of the requirement offered by the Obama administration.

Among those mounting objections are the Little Sisters of the Poor, an order of Roman Catholic nuns that runs care homes for the elderly.

The court, divided 4-4 between liberal and conservative justices without the conservative Scalia, is set to hear the case on Wednesday.

Scalia was considered a reliable vote for the religious groups. In 2014, he was in the majority when the court ruled 5-4 that family-owned companies run on religious principles, including craft retailer Hobby Lobby Stores Inc, could object to the provision for religious reasons.

If the four conservatives who sided with Scalia in that case remain unified, the best result the challengers could get would be a 4-4 split. That would leave in place lower-court rulings that favored the Obama administration.

“Unless the court’s four justices in the dissent in Hobby Lobby dramatically change their minds, the likely worst outcome for the government would be a 4-4 split,” said Gregory Lipper, a lawyer with Americans United for Separation of Church and State, which filed a brief backing the Obama administration.

Lawyers for the challengers forecast that they can win, citing among other things the fact that women can obtain alternative coverage via Obamacare’s online marketplace.

“The idea that the government doesn’t have some other way to do this is really a pretty silly argument,” said Mark Rienzi, a lawyer with the Becket Fund for Religious Liberty, which represents the Little Sisters.

The Christian groups object to a compromise first offered by the federal government in 2013. It allows groups opposed to providing insurance covering contraception on religious grounds to comply with the law without actually paying for the coverage required by the 2010 Affordable Care Act, widely known as Obamacare.

Groups can certify they are opting out by signing a form, which they submit to the government. The government then asks insurers to pick up the tab.

The groups contend the accommodation infringes on their religious rights because it forces them to authorize the coverage for their employees, even if they are not paying for it.

A ruling is due by the end of June.