Legislation that would allow a range of benefits for same-sex domestic partners of federal employees gained a boost last week with the announcement of 20 new Senate cosponsors and the endorsement of 35 organizations.

The announcement from the bipartisan chief sponsors of the bill, Sens. Joseph I. Liebermam (I-Conn.) and Susan Collins (R-Maine), came in the wake of the Obama administration’s decision to allow, for the first time, employer-sponsored health benefits for the same-sex partner of a federal worker.

That decision, however, only affected a single employee, Karen Golinski, a federal lawyer in California. She successfully sued in federal district court to have the Defense of Marriage Act, also known as DOMA, declared unconstitutional. DOMA says marriage is between heterosexuals. Until now it has prevented the government from providing benefits to all its staffers.

In addition to health benefits, under theLieberman/Collins Domestic Partnership Benefits and Obligations Act, same-sex domestic partners of federal workers living together in a committed relationship could get retirement, family and medical leave, and long-term care benefits.

The bill would place the government with almost 60 percent of Fortune 500 companies, including top federal contractors, and 50 percent of employers with 5,000 or more workers, 24 states and several hundred local jurisdictions that offer benefits to the same-sex domestic partners of their employees, according to Lieberman’s office.