WASHINGTON — The US Senate will vote this week on a bill to protect same-sex marriage, Democratic Senate leader Chuck Schumer said Monday, after an agreement reached between members of both parties.

In the United States, same-sex unions have been guaranteed by the Supreme Court since 2015.

But after the court’s historic overturning of a longstanding ruling protecting the right to abortion, many progressives fear that same-sex marriage may also be under threat.

In mid-July, the House of Representatives passed a law to protect such unions across the country. All House Democrats and 47 Republicans supported the bill, but nearly 160 Republicans opposed it.

In the Senate, negotiations have been underway for weeks to ensure the support of at least 10 Republicans for the bill, the number needed for it to pass under qualified majority rules.

A bipartisan group of senators announced on Monday that an agreement had been reached.

The bill is a “needed step” to grant millions of couples “the certainty that they will continue to enjoy the freedoms, rights and responsibilities afforded to all other marriages,” said Democratic Senator Kyrsten Sinema.

A first procedural vote on the bill, which also protects interracial couples, will be scheduled for Wednesday, Schumer said.

He urged the conservative opposition to line up behind the bill, which he described as “extremely important.”

A large majority of Americans support same-sex marriage, including in Republican ranks. But the religious right remains mostly opposed to it.

The Republican minority leader, Mitch McConnell, who wields great influence over his caucus, has not yet indicated whether he will vote in favor of the bill.