A crowd celebrates outside the Supreme Court in Washington on June 26 after the court declared that same-sex couples have a right to marry anywhere in the United States. (Jacquelyn Martin/Associated Press)

A coalition of liberal Democrats began a new campaign Thursday with a broad proposal to rewrite the landmark 1964 Civil Rights Act to outlaw discrimination against gays in the workplace, in financial and housing markets, and in other areas of private and public life. Proponents describe the effort as the next gay rights movement.

The legislation, dubbed the Equality Act, comes less than a month after a Supreme Court ruling that made same-sex marriage legal nationwide, a 5 to 4 decision that prompted lawmakers who support gay rights and their political allies to set aside legislation that was more modest in scope and to advance a more comprehensive bill.

“The time has come to not just focus on one small piece of the puzzle,” Sen. Jeff Merkley (D-Ore.), the lead Senate sponsor of the measure, said in an interview before Thursday’s formal news event announcing the effort.

Merkley and his supporters had previously pushed legislation to protect lesbian, gay, bisexual and transgender workers from discrimination, winning passage last year of the Employment Non-Discrimination Act for the first time in the Senate. The measure died in the House.

Rather than revive that legislation, supporters said the court ruling gave them the legal and political momentum to advance the much broader bill. “I think America is ready to take more steps forward,” said Sen. Tammy Baldwin (D-Wis.), a co-sponsor of the bill and the only openly lesbian senator.

How same-sex marriage became legal across the country

The proposal would grant gay people the same protections African Americans and other minorities have from discrimination in employment, credit, the housing market, jury selection and other public accommodations.

Baldwin and other supporters acknowledge that it will be a long process to win approval in a Congress that is firmly under the control of Republicans, not one of whom has co-sponsored the legislation.

“This is going to be the heaviest lift in the history of our movement,” said Chad Griffin, president of the Human Rights Campaign, the nation’s largest gay rights advocacy group.

Griffin said the court’s ruling on same-sex marriage gave the coalition the political impetus to press for a comprehensive non-discrimination proposal. That’s because public support for non-discrimination proposals for gay rights has regularly polled higher than same-sex marriage, and at the state level, many legislatures first advanced non-discrimination laws before they backed marriage rights.

Rep. David N. Cicilline (D-R.I.), who is leading the House effort, announced Thursday that 155 House Democrats have co-sponsored the legislation, as have dozens of Senate Democrats. They include Rep. John Lewis (D-Ga.), an icon of the civil rights movement, and Sen. Cory Booker (D-N.J.), one of two black senators.

Booker said that some veterans of the civil rights movement are reluctant to endorse the effort to expand gay rights. Those leaders come from a “first, do no harm” mindset when it comes to the Civil Rights Act, Booker said, fearful that any bid to reopen the law could lead to efforts to scale back the rights that it affords minorities and women.

In Thursday’s rally introducing the legislation, Lewis linked the push to ensure full gay rights to the marches he participated in during the 1950s and 1960s. “It is our mission,” he said. “Let’s do the right thing.”

At the moment, the NAACP has not endorsed the Equality Act, but Booker said he is working to get more support from black leaders. Other supporters noted that although some of the groups have hesitated to endorse the legislation, they have not opposed it outright.