The U.S. Senate on Wednesday will hold an initial vote on legislation to protect the right to same-sex marriage, spurred by concerns that a conservative Supreme Court could reverse its earlier decision that made it legal nationwide.

The bill, which is expected to pass the Senate, would serve as a legal backstop against any future Supreme Court action by requiring the federal government recognize any marriage that was legal in the state it was performed.

However, it would not block states from banning same-sex or interracial marriages if the Supreme Court allows them to do so.

Supporters of same-sex marriage were spurred to act when Supreme Court Justice Clarence Thomas wrote that the court should also reconsider the legality of same-sex marriage, in a concurring opinion to the court’s overturning of federal protections for abortion in June.

There are roughly 568,000 married same-sex couples in the United States, according to the U.S. Census Bureau.

“I’ve heard from constituents back home who are concerned and worried about the suggestion that their right to marry who they love will be taken away,” Democratic Senator Tammy Baldwin, the first openly gay person elected to the Senate, said at a press conference on Tuesday.

Although same-sex marriage has gone from a political hot potato to a well-established norm in the past decade, the bill’s negotiators have still had to thread a needle between protecting a right most Americans now see as a given, and assuaging concerns from Republican senators about religious liberties.

The legislation, which must get support from 60 senators in the evenly divided chamber to pass, is the result of months of negotiating by Baldwin and fellow Democrat Kyrsten Sinema, along with Republican senators Susan Collins, Thom Tillis and Rob Portman.

A similar bill passed in the House in July, with the support of 47 Republicans along with all of the chamber’s Democrats.

The bill will have to jump through several more procedural hoops in the Senate before going back to the House for final approval.