Backers of Proposition 8 said on Tuesday that they would appeal a federal appeals court decision to the Supreme Court.

“The 9th Circuit's decision to deny an en banc hearing comes as no surprise,” tweeted ProtectMarriage, the group which sponsored the 2008 voter-approved amendment. “We will promptly file our appeal to the US Supreme Court.”

“We look forward to a positive outcome on behalf of millions of Californians who believe in traditional marriage.”

The reaction came within hours of the Ninth Circuit Court of Appeals' announcement that it would not rehear Perry v. Brown, the case challenging the constitutionality of Proposition 8.

The measure put an end to the legal weddings of gay and lesbian couples taking place in California after the state Supreme Court ruled that the state's law limiting marriage to heterosexual couples is unconstitutional. Approximately 18,000 gay couples married before Proposition 8 went into effect.

In February, a 3-judge panel of the appeals court upheld a lower court's ruling which found Prop 8 in violation of the constitutional rights of gay couples who wish to marry in California.

The sponsors of the ban asked the court for an en banc review, which would expand the number of judges reviewing the case to 11.

(Related: Gay groups cheer federal appeals court's decision to not revisit Prop 8 case.)