Thirty-seven senators are calling on President Barack Obama to sign an executive order prohibiting workplace discrimination against gay, bisexual and transgender Americans by federal contractors.

“Issuing an executive order that includes sexual orientation and gender identity is a critical step that you can take today toward ending discrimination in the workplace,” the senators wrote in a letter to the president. “By expanding protections for LGBT employees of federal contractors, you would be helping to ensure that all Americans get an equal opportunity to succeed and that federal taxpayer dollars are used to support companies with the best employment practices.”

Obama decided against signing such an order last year and called on the Congress to pass broader legislation introduced by Democratic Senators Jeff Merkley of Oregon and Tom Harkin of Iowa and Republican Senators Mark Kirk of Illinois and Susan Collins of Maine.

However, the Employment Non-Discrimination Act (ENDA) has stalled in the Republican-controlled House.

Defense contractors have been prohibited from discriminating based on race or national origin since World War II, and broader anti-discrimination bans have been in place on all contractors for almost 50 years.

Signing on to the letter organized by Senator Merkley are: Tom Harkin (D-IA), Patty Murray (D-WA), Chris Coons (D-DE), Jeanne Shaheen (D-NH), Mazie Hirono (D-HI), Sheldon Whitehouse (D-RI), Richard Blumenthal (D-CT), Ron Wyden (D-OR), Patrick Leahy (D-VT), Barbara Boxer (D-CA), Tom Udall (D-NM), Al Franken (D-MN), Dianne Feinstein (D-CA), Claire McCaskill (D-MO), Tammy Baldwin (D-WI), Martin Heinrich (D-NM), Kirsten Gillibrand (D-NY), Carl Levin (D-MI), Elizabeth Warren (D-MA), Frank Lautenberg (D-NJ), Amy Klobuchar (D-MN), Barbara Mikulski (D-MD), Sherrod Brown (D-OH), William Cowan (D-MA), Mark Udall (D-CO), Dick Durbin (D-IL), Debbie Stabenow (D-MI), Bernie Sanders (I-VT), Chuck Schumer (D-NY), Brian Schatz (D-HI), Mark Begich (D-AK), Mark Warner (D-VA), Ben Cardin (D-MD), Jack Reed (D-RI), Robert Casey (D-PA), and Robert Menendez (D-NJ).