Those lobbying for the executive order say there's ample precedent, notably a 1941 order by President Franklin D. Roosevelt banning workplace discrimination by defense contractors on the basis of race, religion or national origin.
Among current federal contractors, most of the large firms already have nondiscrimination policies covering sexual orientation. But the Williams Institute, a gay-rights think tank at the University of California, Los Angeles, estimates that 16.5 million employees work for contractors that lack such policies.
Cathcart said Lambda Legal receives many hundreds of calls annually from gays and lesbians reporting job discrimination — justification, in his eyes, for keeping the heat on Obama despite his strong record on gay rights.
"It's true there's been a lot of breakthroughs, but I don't think breakthroughs happen without a lot of outside pressure," Cathcart said.
Tico Almeida of Freedom to Work, one of the advocacy groups leading the push for the executive order, said he has met twice with White House aides. He is confident Obama eventually will sign the order and maintains "a sliver of optimism" that it could happen this spring.
"They need to rip this off like a Band-Aid," Almeida said. "The drumbeat is going to continue for months and months, and the best way to have this become a nonissue is to do it quickly."
If that doesn't happen, he said, the pressure will continue. His group is making plans to fly victims of anti-gay workplace discrimination to Washington to seek meetings with White House staff.
Obama aides at the White House and in his re-election campaign say the administration understands the frustration within the gay-rights community, but they depict overall relations as constructive despite some tactical differences. While trying to keep gay and lesbian voters energized, they have tried to tamp down expectations that Obama might declare his support for gay marriage before the election.
As for the gay-rights plank to be considered at the Democratic convention, the platform writing committee has yet to be formed. It's unclear at this stage how far, if at all, the language it adopts might go beyond Obama's current position on same-sex marriage, which he describes as "evolving."
Andrew Tobias, treasurer of the Democratic National Committee — and gay himself — predicted that the platform committee would adopt language emphatically supporting equality for gay and lesbian families.
"It was a very strong platform in 2008 and I would expect it to be even stronger this year," he said.
Among those urging adoption of a marriage-equality plank is Los Angeles Mayor Antonio Villaraigosa, who is the convention chairman and a co-chairman of Obama's re-election campaign. Numerous Democratic senators have endorsed the proposed plank, as has House Minority Leader Nancy Pelosi.
Evan Wolfson, president of the advocacy group Freedom to Marry, says Obama and his advisers should take heed of opinion polls showing that a majority of independent voters, as well as Democrats, support same-sex marriage.
"He has very little to lose and a lot to gain by standing where the majority of Americans are, where voters that he needs want him to be," Wolfson said. "Sometimes political operatives can be overly cautious, but 2012 is not the time for that."
Rep. Jared Polis, D-Colo., one of four openly gay members of Congress, said he wished Obama would be "more aggressive" in banning anti-gay bias in the federal workforce. Regarding the party platform, however, he suggested a confrontation over marriage was not inevitable.
"When you have a platform for a broad coalition, you will have some parts that not everyone agrees with," he said.
Ethan Geto, a New York consultant who has advised Hillary Rodham Clinton and other Democrats on gay-rights issues, recommended that Obama sign the workplace executive order swiftly but said the marriage issue was more complicated.