Gay partners could receive health and pension benefits under the new rules
US President Barack Obama has signed a measure extending benefits to same-sex partners of federal government workers.
The move comes amid anger from Mr Obama's gay supporters that he has not done enough to protect the rights of gay Americans.
He has been criticised for failing to repeal the ban on gays in the US military and over a Justice Department legal opinion opposing gay marriage.
Several gay supporters have withdrawn from a fundraising event in protest.
Mr Obama's presidential order means that the gay partners of federal employees will get some health benefits currently enjoyed by the heterosexual partners of government workers.
The federal government is the largest employer in the US.
Employees' partners can now be added to a government insurance programme paying for long-term conditions, such as Alzheimer's disease.
They will also be allowed to take sick leave to care for a sick partner or non-biological child, the Associated Press reported.
However, the new order doesn't extend health care benefits or pensions for partners as many had hoped.
"We all have to acknowledge this is only one step," Mr Obama said in the Oval Office as he signed the order.
But what is being seen as an incremental step forward was not well-received by critics.
"When a president tells you he's going to be different, you believe him," John Aravosis, a Washington-based gay activist was quoted by AP as saying.
"It's not that he didn't follow through on his promises, he stabbed us in the back."
Gay rights activists have been disappointed with Mr Obama
During the presidential election campaign, Mr Obama expressed opposition to gay marriage.
Instead, he supported civil unions, which would give gay couples the same legal and financial benefits as married heterosexual couples.
Mr Obama has indicated his opposition to the US military's "Don't Ask, Don't Tell" policy, under which gay servicemen and women are allowed to serve, but only if they do not publicly disclose their sexuality or engage in homosexual acts.
But since entering the White House, Mr Obama has done nothing to overturn the policy, and has declined to intervene in the cases of gay soldiers who have been thrown out of the military for being gay.
Administration officials say the president is seeking to repeal "Don't Ask, Don't Tell" as part of a "lasting and durable" solution, which precludes interventions in individual cases.
"The president agreed that... the policy wasn't working for our national interests, that he committed to change that policy, that he's working with the Secretary of Defence and the joint chiefs on making that happen," said White House spokesman Robert Gibbs last month.
Mr Obama's failure to repeal the military ban is not the only issue that has frustrated gay rights campaigners.
Last week, the Department of Justice (DoJ) issued a legal opinion in response to a lawsuit challenging the legality of the Defence of Marriage Act, which defines marriage as being between a man and a woman.
The DoJ opinion sparked outrage in the gay community, because it compared same-sex marriages to incestuous and underage marriages.
A justice department spokesperson insisted that the president is opposed to the Defence of Marriage Act, but that until the act is repealed in Congress, the DoJ has a duty to defend the law as it stands.
But the controversial opinion prompted at least three prominent gay donors to the Democratic Party to withdraw from a party fundraiser, which is due to take place on 25 June.