Gov. Charlie Baker and Lt. Gov. Karyn Polito are among more than 400 Republican, Libertarian and conservative leaders across the country calling on the U.S. Senate to pass a bill officially writing marriage equality into federal law.

Baker, Polito and a handful of other prominent Republican Bay Staters signed on to a letter, also published as an ad in the Wall Street Journal, that calls civil marriage "a fundamental freedom central to individual liberty and the pursuit of happiness." Referencing a May survey from Gallup, the letter says its signatories "stand with the 71 percent of Americans today, including a majority of registered Republicans, who support the freedom to marry for all Americans."

The letter, compiled by the centrist policy nonprofit Centerline Action and the coalition Conservatives Against Discrimination, urges the Senate to pass a bill dubbed the Respect for Marriage Act that formally provides statuatory authority for same-sex and interracial marriages. The House passed the bill in July, as a way to push back against a Supreme Court that’s signaled an interest in rolling back past rulings.

When the court’s conservative majority in June overturned Roe v. Wade, Justice Clarence Thomas wrote a concurring opinion that also suggested reconsidering precedents involving birth control and same-sex marriage.

An advertisement, cropped to show the top, begins "Republicans & Conservatives Across America Call on the U.S. Senate to Preserve the Freedom to Marry"
Gov. Charlie Baker Baker, Lt. Gov Karyn Polito and a handful of other prominent Republican Bay Staters signed on to a letter that calls civil marriage "a fundamental freedom central to individual liberty and the pursuit of happiness."
Courtesy of Gov. Charlie Baker’s office

Carol Rose, executive director of the ACLU of Massachusetts, said the letter circulated Wednesday "reflects the fact that the Supreme Court has become increasingly hostile to protecting fundamental rights," leaving that task to state leaders. Voters, she said, want to see their elected officials act on these issues.

"These Republican and independent leaders are recognizing that they ignore that public opinion at their political peril," Rose said.

In Massachusetts, Rose said Republican and independent leaders should "join Democrats in standing up for these basic fundamental due process rights that are being threatened by the Supreme Court."

"It's incumbent upon everybody who cares about democracy and fundamental freedoms to raise their voice," she said.

Along with Baker and Polito, other Massachusetts figures who signed the letter include former Gov. Jane Swift, former U.S. Sen. Scott Brown, former state Senate minority leader and Baker’s 2010 running mate Richard Tisei, and Patrick Guerriero, who served as both a state representative and mayor of Melrose. Guerriero was also a lieutenant governor candidate in 2002 as Swift’s running mate, though they each dropped out of that race before the election.

Among the notable signatories from other states are former U.S. Sen. Olympia Snowe of Maine, current Senate candidates Mehmet Oz of Pennsylvania and Joe O'Dea of Colorado, political commentator and television personality S.E. Cupp, and two aides from the Trump White House -- former communications director Michael Dubke and former assistant to the president Alyssa Farah Griffin.

"Millions of our fellow Americans in same-sex and interracial marriages need, and should have, the confidence and certainty that their marriages are legal," former Florida Congresswoman Ileana Ros-Lehtinen, co-chair of Conservatives Against Discrimination, said in a statement.