The U.S. Supreme Court on Wednesday refused to halt same-sex weddings in Oregon while a federal appeals court considers whether a group opposed to gay marriage can intervene in the case.

The order follows an emergency appeal by the National Organization for Marriage, which seeks to overturn U.S. District Judge Michael McShane's May 19 ruling that declared Oregon's same-sex marriage ban unconstitutional. The group had unsuccessfully tried to intervene in the lower court proceeding after Oregon Attorney General Ellen Rosenblum declined to defend the same-sex ban.

The group filed its request with Justice Anthony Kennedy and he referred it to the full court. The justices denied it without comment.

Hundreds of same-sex couples have obtained marriage licenses since McShane's order, including 245 in Multnomah County, the state's largest.

The Oregon case differs from others where the Supreme Court or federal appeals judges have temporarily blocked lower-court rulings, halting same-sex unions while appeals proceed.

In Oregon, the appeal is focused on whether an outside group can intervene in the case, not on the constitutionality of the same-sex marriage ban, so it raises a different set of legal questions.

Lawyers for the attorney general's office have said they won't appeal McShane's ruling and are fighting the National Organization for Marriage's appeal in the 9th U.S. Circuit Court of Appeals.

Rosenblum, the attorney general, said there were no legal arguments she could offer in defense of the marriage ban that would be consistent with decisions last year by the U.S. Supreme Court and with state laws.