The Senate voted 61-36 on Tuesday to pass a bill that would enshrine gay marriage in federal law, requiring require individual states to recognize another state's legal marriage.
The Respect Marriage Act now moves to the House, where it is expected to pass in the final days of Democratic control and be signed by President Joe Biden.
Opponents contend the bill's stated protections for religious liberty would not stand up in court. They argue the bakers, florists and others in the wedding industry who have been punished for acting on their belief that marriage is a lifelong conjugal union between one man and one woman would be even more susceptible to prosecution.
An amendment to safeguard religious liberty. proposed by Sen. Mike Lee, R-Utah, failed, 49-48.
"Without the protections provided in my amendment, it will be open season on the rights of the faithful," he wrote on Twitter before the vote.
A dozen Republican senators voted for the bill: Roy Blunt of Missouri, Richard Burr of North Carolina, Shelley Moore Capito of West Virginia, Susan Collins of Maine, Joni Ernst of Iowa, Cynthia Lummis of Wyoming , Lisa Murkowski of Alaska, Rob Portman of Ohio, Mitt Romney of Utah, Dan Sullivan of Alaska, Thom Tillis of North Carolina and Todd Young of Indiana.