The justices seemed reluctant to accept the arguments put forth by the religious group known as the Summum that once a government accepts any donations for display in a public park, it must accept them all.

"Do we have to put any president who wants to be on Mt. Rushmore?" Chief Justice John Roberts asked.

Yet the court also was uncomfortable with the position of Pleasant Grove City, Utah, which rejected the Summum's request to erect a monument similar to a Ten Commandments display that has stood in the city's Pioneer Park since 1971.

Justice David Souter wondered how the city could accept the Ten Commandments display and then say, "'We will not on identical terms take the Summum monument because we don't agree with the message.' Why isn't that a First Amendment violation?"

The Salt Lake City-based Summum wants to erect its "Seven Aphorisms of Summum" monument in the park.

The Summum argued, and a federal appeals court agreed, that Pleasant Grove can't allow some private donations in its public park and reject others.