The Human Rights Campaign (HRC), the largest LGBT organization in the country, endorsed Hillary Clinton for president Tuesday.

“All the progress we have made as a nation on LGBT equality – and all the progress we have yet to make – is at stake in November,” HRC President Chad Griffin said in a press release Tuesday. “We are proud to endorse Hillary Clinton for president, and believe that she is the champion we can count on in November – and every day she occupies the Oval Office.”

The 32-member board of HRC endorsed Clinton by a unanimous vote this weekend.

“The board felt that Hillary Clinton has laid out the most robust plan in the campaign on LGBT issues,” HRC spokesman Brandon Lorenz told The Christian Science Monitor in a phone interview Tuesday. “They thought she was best equipped to fight for us and our issues and do so during the general election.”

Mr. Lorenz tells the Monitor that the board used three pillars of endorsement criteria: “support for issues of concern to the community, demonstrated leadership on LGBT issues and viability” in the 2016 election.

Clinton faced a tough competitor for the endorsement. Vermont Sen. Bernie Sanders was one of the country’s first political supporters of LGBT rights, officiating a Gay Pride Day as Mayor of Burlington in 1983. In 1996, Sanders was one of only 67 members in the House of Representatives who opposed the Defense of Marriage Act, a law that barred all federal recognition of same-sex marriage. HRC even awarded Sanders a perfect score – 100 percent – on its Congressional Equality Index.

But for Clinton, a history of support is not necessarily a prerequisite for future leadership.

“You know, somebody is always first,” Clinton tells NPR’s Terry Gross in a 2014 interview regarding her political evolution on gay rights. “But that doesn’t mean that those who joined later in being publicly supportive or even privately accepting that there needs to be change are any less committed. You could not be having the sweep of marriage equality across our country if nobody changed their mind. And thank goodness so many of us have.”

And LGBT leaders tend to agree: first doesn’t mean best.

“Secretary Clinton has made LGBT equality a pillar of her campaign and recently unveiled the most robust and ambitious LGBT plan any candidate for president has ever laid out,” HRC writes in their press release.

Both Sanders and Clinton list LGBT equality goals as part of their campaign platforms, such as signing the Equality Act, which would add LGBT protection federal civil rights law, ensuring better police education on LGBT issues.

But it is in her almost 3,000-word briefing that Clinton outshines Sanders in the eyes of many LGBT rights activists, announcing detailed policy initiatives such as dropping the ban on open transgender military service, correcting the records of military members who were wrongfully discharged under the "Don’t Ask, Don’t Tell" policy, ending LGBT conversion therapy for minors and securing affordable treatment for people with HIV and AIDS.

“[Clinton] has a long record of being a strong advocate for LGBT rights and for being a leader in the debate – especially when she was in Congress and as Secretary of State,” Richard Socarides, a Democratic political commentator and former aide to President Bill Clinton, told The Christian Science Monitor in a phone interview Tuesday. “Bernie Sanders, while he may have voted correctly, he has not been a leader, he has not been at the center of any of these debates.”

But Clinton’s history on LGBT rights has not been completely ignored.

On MSNBC's "The Rachel Maddow Show" in October, Clinton tried to defend her husband’s signing of the 1996 Defense of Marriage Act, on the grounds that it successfully prevented an equivalent Constitutional amendment.

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But those who were there at the time saw no signs of a more restrictive law in the works. “It’s ridiculous. There was no threat in the immediate vicinity of 1996 of a constitutional amendment. It came four years later,” Elizabeth Burch, executive director of HRC from 1995 to 2004, told the Huffington Post in response to Clinton’s comments. It may be that she needs to revisit the facts of what happened.”

Clinton also has other ties to HRC leadership. HRC President Griffin, who began his career in the White House Press Office under President Bill Clinton, has voiced his personal support for Hillary. Some of HRC’s top corporate partners include CitiBank, Goldman Sachs, and Morgan Stanley – all three of which are also present on Clinton’s Top Ten Donor list.