By Julie Moreau

Following Sunday’s New York Times report about a leaked Trump administration memo that proposed narrowing the definition of sex in such a way that would — as The Times described — define transgender people “out of existence,” LGBTQ advocates quickly embarked on a mobilization effort.

In the draft memo, which has not been viewed by NBC News, the U.S. Department of Health and Human Services (HHS) argued that the government must adopt a uniform definition of sex “on a biological basis that is clear, grounded in science, objective and administrable,” the Times reported.

Diana Flynn, litigation director at LGBTQ advocacy group Lambda Legal, called the alleged HHS proposal “jaw-dropping.”

“HHS would be calling on the federal agencies that enforce parts of Title IX — including the Departments of Labor, Justice and Education in addition to HHS — to accept its completely arbitrary definition of what constitutes a person’s ‘sex’ for purposes of applying federal antidiscrimination law in aspects of life ranging from education to employment to health care,” Flynn said in a statement shared with NBC News.

Lambda Legal was among more than a dozen LGBTQ and civil rights groups that participated in a joint press conference Monday morning promising to fight any efforts to limit legal protections for transgender people and calling for transgender people and their allies to make their voices heard at the ballot box next month.

Mara Keisling, executive director of the National Center for Transgender Equality, characterized the administration’s actions as part of a “reckless, hateful agenda.”

“If you come for LGBTQ people, we are coming for you on election day,” Keisling said at the press conference.

JoDee Winterhof of the Human Rights Campaign, a national LGBTQ rights group, urged the LGBTQ community and allies to “turn out in force” on Nov. 6.

“Reject the politics of hate and discrimination and send a pro-equality majority to Congress,” Winterhof said, echoing Keisling.

Following Monday morning’s press conference, a protest was held in front of the White House that drew several hundred people. During the rally, protesters chanted “trans rights are human rights,” and community leaders addressed the crowd and vowed to fight any potential rollback in transgender rights.

“We’re going to vote for pro-LGBT-equality legislators up and down the ballot across the country, because this is not a red or blue issue, this is a human issue,” Masen Davis, CEO of Freedom for All Americans, said as he addressed the crowd.

A social media campaign using the hashtag #WontBeErased was trending on Twitter on Monday. LGBTQ advocates and allies — including lawmakers and celebrities — used the hashtag to support the transgender community and voice opposition to the proposal in the leaked memo.

While she didn’t use the trending hashtag, Hillary Clinton also took to Twitter to call out the “attack on the humanity of transgender people.”

Diana Flynn of Lambda Legal called the leaked memo “another ideologically-driven attempt by the Trump administration to marginalize transgender people and force them into the shadows.”

Since Trump took office, his administration has revoked guidelines at the Department of Education that extended anti-discrimination protections to transgender students; reversed a policy at the Bureau of Prisons on consideration of gender identity in housing decisions; issued a memo at the Department of Justice that Title VII does not protect transgender workers from discrimination; and sought to prevent transgender people from serving in the military.

When asked about the draft memo reported on by The New York Times, HHS, where the memo reportedly originated, would not comment.

“We do not comment on alleged leaked documents,” a spokesperson told NBC News.

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