"We may not ever be able to count on this administration to lead on LGBT issues," Clinton said in a speech in New York.
Clinton was addressing a fundraising dinner for The Center, an LGBT community organization, where she received an award and thanked members of the audience for supporting her unsuccessful 2016 presidential bid. But she told those gathered there to watch out for "the progress that we fought for, that many of you were on the front lines for."
"It may not be as secure as we once expected," she said.
The event was yet another public foray for Clinton, who in the weeks and months immediately after her electoral upset, generally did not comment on politics. More recently, however, she has used speaking events
to lay into Trump and the Republican Party.
At her speech Thursday evening, she listed several controversial moves by the Republican administration and stressed their importance.
"When this administration rescinded protections for transgender students, my heart broke," Clinton said. "When I learned about the proposed cuts in funding for HIV and AIDS research, I thought about all of our efforts to try and achieve an AIDS-free generation."
Clinton criticized Trump in particular for his decision to nominate Mark Green, who she called an "outspoken opponent" of LGBT rights, to replace former Army Secretary Eric Fanning, the first openly gay man to hold the job.
"Some of the changes that we're seeing should seem small, but they matter a great deal if you're the person affected," Clinton said. "Others carry historic significance, like the future of the Supreme Court."
She called on attendees to participate in organizations that would foster progress on human rights and for the United States to call out abuses of gay people abroad, like the reported homophobic killings in Chechnya. She said due to the Trump administration's posture on gay rights, people needed to "never stop fighting" and focus on winning upcoming elections, from the midterms on.
"I know the election hit a lot of us hard," Clinton said, pausing for laughs before continuing. "I can tell you this: Even when it feels tempting to pull the covers over your heads, please keep going."
Clinton's historic stances on same-sex marriage have often been criticized, too. When her husband was president, he signed the Defense of Marriage Act into law, which stood for years as a roadblock to marriage equality.
Clinton herself was publicly opposed to same-sex marriage for years, gradually changing her tone before fully embracing
marriage as a right regardless of sexual orientation sometime between her 2008 campaign and a 2013 video
on behalf of the Human Rights Campaign.
As secretary of state, she declared, "gay rights are human rights," echoing her famous words in China as first lady. She repeated the statement Thursday evening, to sustained applause.