SALT LAKE CITY — A group of Republicans has come out in support of legalizing gay marriage in Utah and Oklahoma, arguing that allowing same-sex unions is consistent with the Western conservative values of freedom and liberty once championed by Ronald Reagan and Barry Goldwater.

Led by former Sen. Alan Simpson of Wyoming and former Sen. Nancy Kassebaum of Kansas, 20 Republicans signed a friend of the court brief submitted Tuesday to a federal appeals court in Denver that is reviewing same-sex marriage bans in Utah and Oklahoma.

The list also includes former New Mexico Gov. Gary Johnson, former Republican National Committee chairman Kenneth Mehlman and several state legislators from Wyoming and Colorado. Melhman came out as gay in 2010 and has worked to bring together Republicans willing to step forward in support of gay marriage.

Denver attorney Sean Gallagher, whose firm wrote the 30-page argument, said the filing shows that many prominent Republicans are re-examining their stance on gay marriage.

The group call themselves “conservatives, moderates and libertarians who embrace the individual freedoms protected by our Constitution,” embrace Reagan’s idea of the Republican Party being a “big tent,” and share Goldwater’s belief that the party shouldn’t “seek to lead anyone’s life for him,” the brief says.

“It is precisely because marriage is so important in producing and protecting strong and stable family structures that (we) do not agree that the government can rationally promote the goal of strengthening families by denying civil marriage to same-sex couples,” the argument says in the conclusion.