WASHINGTON -- The transgender rights movement in the United States has suddenly found itself inserted into the battle for control of Capitol Hill.

With U.S. midterms just two weeks away, an internal Department of Health and Human Services memo leaked to the New York Times proposes defining gender as an immutable biological condition determined by a person's sex organs at birth.

The report brought an onslaught of protesters to the front lawn of the White House earlier this week, accusing U.S. President Donald Trump's administration of eroding LGBTQ rights and trying to legislate transgender Americans out of existence.

It also triggered a backlash on social media, fuelled by the hashtag "WontBeErased."

Trump says the government is looking "very seriously" at making changes, but has so far refused to offer much detail, saying only, "I'm protecting everybody."

It wouldn't be the first time the administration has targeted transgender rights, having scrapped efforts to allow students to use their preferred school bathroom, excluding them from civil rights protections at work and trying -- unsuccessfully -- to ban transgender people from military service.