U.S. Rep. Joe Kennedy III, D-Brookline, continued push back Friday against the Trump administration's efforts to define "sex" as a biological condition, urging officials to reject the "brazen, targeted attack" on transgender Americans.

Kennedy, the Congressional LGBT Caucus' Transgender Equality Task Force chairman, led nearly 100 lawmakers in a letter calling on U.S. Department of Health and Human Services Secretary Alex Azar to oppose efforts to redefine "sex" as being based on biology in the civil rights law that bans gender discrimination in federally funded education programs.

Arguing that "adoption of this cruel and unscientific definition of sex would undermine enforcement of civil rights for millions," the congressman pressed Azar to "stop any attempt by extremists within the Department of Health and Human Services to infringe upon the dignity, rights and lives of transgender people."

Kennedy added that the proposal's "narrow language disregards Supreme Court and circuit court case law precedent and could only be part of a deliberate strategy to eliminate federal protections for transgender people and further marginalize an at-risk minority group."

He further contended that it raises various practical, legal, medical and privacy questions.

The congressman, for example, offered that transgender individuals could be denied access to medical care or health insurance, as well as be refused access to emergency shelter and public housing under the proposed policy change.

Kennedy and other lawmakers urged Azar to "stand up to these extremists and prevent this dangerous proposal from ever becoming department or administration policy."

"This administration cannot ethically or legally decide to ignore all science and precedent to unilaterally render the promise of civil rights meaningless for transgender Americans," he said in a statement. "Even for a president who traffics in fear and conspiracy, this policy scrapes the deepest depths of bigotry. To every single transgender American, you will not be erased because you are heard, you are seen and you are counted."

.@RepJoeKennedy has a message for all the young trans people out there - you are seen, you are heard, you are loved, and you #WontBeErased. pic.twitter.com/CsjsAGasuX — National Center for Transgender Equality (@TransEquality) November 2, 2018

The letter came just weeks after the New York Times reported that HHS was pushing government agencies to adopt a uniform definition of gender based on biology, "that is clear, grounded in science, objective and administrable."

The agency had proposed defining it as either "male or female, unchangeable and determined by the genitals that a person is born with," according to the newspaper.

Kennedy initially condemned the reported effort as "pure politics and politics at its worst," adding that it's even more important for Massachusetts voters to support a state ballot question to uphold a July 2016 law that added gender identity to the list of prohibited grounds for discrimination in places of public accommodation.