The Episcopal bishop will offer the prayer at the Lincoln Memorial on Sunday, January 18. President-elect Obama and Vice President-elect Biden are both expected to attend.

"Bishop Robinson models what prayer should be--spiritual reflection put into action for justice,” Human Rights Campaign President Joe Solmonese said. "It is encouraging that the President-elect has chosen this spiritual hero for all Americans to lead the nation in prayer at the Lincoln Memorial inaugural concert.” Robinson is also a member of HRC's Religion Council.

"President-elect Obama has made a stellar choice in selecting Bishop Gene Robinson," added Rea Carey, Executive Director of the National Gay & Lesbian Task Force. "Bishop Robinson is an inspiration to millions worldwide because he lives out the ideals of courage, humility and truth speaking. This is certainly a good sign that our nation is indeed moving forward...President-elect Obama's wise choice of Bishop Robinson, as well as that of Rev. Lowery and Rev. Watkins, continues to add to the historic nature of this inaugural celebration. For the first time in history, an out gay man will lead the nation in opening the transfer of power from one administration to another -- and every person watching in the U.S. and around the world will have seen it. That, alone, is change."

Bishop Robinson has been one of many outspoken critics of Obama's choice of megachurch pastor Rick Warren to deliver the invocation at the January 20 swearing-in.

Robinson, in December, called the pick a "slap in the face." "I'm all for Rick Warren being at the table," he said, "but we're not talking about a discussion, we're talking about putting someone up front and center at what will be the most watched inauguration in history, and asking his blessing on the nation. And the God that he's praying to is not the God that I know."

Warren, of Saddleback Church in southern California, has been quoted in interviews putting same-sex relationships on par with incest and pedophilia, as well as showing an ideological inability to separate committed same-sex relationships from stereotypical "gay promiscuity." Warren was also an outspoken proponent of California's Proposition 8, which, pending the state Supreme Court's final ruling, was narrowly approved by a popular vote in November to revoke marriage rights for same-sex couples affirmed in May.

Warren, in a recent letter, said that he was on Bishop Robinson's "attack list" for his position on marriage equality, and as a "adversary" of the Episcopal Church over his alliances with Anglican leaders such as Nigerian Archbishop Peter Akinola. Certain sects within the Anglican Church, international parent to the Episcopalians, have threatened to secede should the church not specifically bar gays from being ordained.

Obama and Biden have both defended the pick, citing a spirit of inclusion and unity in maintaining support for LGBT people and causes while reaching out to those with whom one might not agree on every issue.

When asked if the Rick Warren controversy was a factor in choosing Robinson, inaugural committee spokesman Clark Stevens said that Robinson had been chosen because he had advised the Obama campaign, and is an "important figure in the religious community. We are excited that he will be involved."

"It's important for any minority to see themselves represented in some way," Robinson told the Concord Monitor on Monday. "Whether it be a racial minority, an ethnic minority, or in our case, a sexual minority. Just seeing someone like you up front matters."

Wire services contributed to this report.