As of 2015, Manchin was the only member of the Senate Democratic Caucus to oppose same-sex marriage. He is the only Democratic senator to not have declared support for same-sex marriage. On February 14, 2018, he cosponsored S.515, a bill that would amend the Internal Revenue Code of 1986 to clarify that all provisions shall apply to legally married same-sex couples in the same manner as other married couples. As of March 18, 2019, he is the only member of the Senate Democratic Caucus who is not a cosponsor of the Equality Act. He has said that he believes “no one should be afraid of losing their job or losing their housing because of their sexual orientation” but does not believe the current version of the Equality Act "provides sufficient guidance to the local officials who will be responsible for implementing it." In March 2021, Manchin was the only Democrat to vote for a failed amendment to rescind funding from public schools that allow trans youth to participate in the sporting teams of their gender identity.