A massive defense policy bill that cleared the House on Wednesday includes a ban on gender-affirming care for children of servicemembers — a provision that sparked opposition from the top Democrat on the House Armed Services Committee and many others in the party.

The bill passed 281-140. Two hundred Republicans and 81 Democrats voted yes, while 124 Democrats and 16 Republicans voted no.

The sweeping must-pass bill — known as the National Defense Authorization Act or NDAA — authorizes spending for the Defense Department and sets defense policies before they expire at the end of the year. It now heads to the Democratic-controlled Senate and must be signed by President Joe Biden to become law.

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The bill was negotiated between senior House and Senate lawmakers. But Rep. Adam Smith, D-Wash., the former Armed Services chairman who is now the panel's ranking member, said he would oppose passage of the NDAA because it includes the ban on gender-affirming care.

"[B]lanketly denying health care to people who need it — just because of a biased notion against transgender people — is wrong," Smith said in a statement Tuesday. "The inclusion of this harmful provision puts the lives of children at risk and may force thousands of service members to make the choice of continuing their military service or leaving to ensure their child can get the health care they need."

Speaker Mike Johnson, R-La., had pushed publicly and behind the scenes for the controversial provision to be included in the package. In a statement after the vote, Johnson said the NDAA refocuses "the Pentagon on military lethality, not radical woke ideology. This legislation permanently bans transgender treatment for minors, prohibits critical race theory in military academies, ends the DEI bureaucracy, and combats antisemitism."

Smith, in his statement, accused Johnson of fighting for the ban in order to appease conservatives in his conference ahead of the Jan. 3 vote to keep him as speaker for another two years.

"Rather than take that [bipartisan] path and ensure service members and military families get the support they need and deserve, he chose to pander to the most extreme elements of his party in an attempt to retain his speakership," Smith said.

Congress typically passes the NDAA with big, bipartisan votes. House Minority Leader Hakeem Jeffries, D-N.Y., told reporters before the vote that his team was not whipping or urging rank-and-file Democratic members to vote one way or the other on the bill. And his leadership team split over the issue: Jeffries, along with Democratic Caucus Chair Pete Aguilar, D-Calif., and Vice Chair Ted Lieu, D-Calif., voted for the defense bill, while Minority Whip Katherine Clark, D-Mass., and Assistant Democratic Leader Joe Neguse, D-Colo., voted no.

The provision in question specifically applies to Tricare, the military's health care program, and would prohibit "medical treatment for military dependents under the age of 18 who are diagnosed with gender dysphoria."

Republicans believe that their attacks on transgender rights during the 2024 campaign helped propel them to victory. And they're now doubling down on that strategy. After the election, Johnson issued a new policy barring transgender women from using women's bathrooms in the House — directly targeting Rep.-elect Sarah McBride, D-Del., the first openly transgender person elected to Congress.

Johnson also played a role in the fight over a provision that would have expanded Tricare coverage to include in vitro fertilization treatment. The speaker "made dropping it a red line demand during negotiations," according to a Senate aide familiar with the talks.

But the speaker's office said the disagreement was more nuanced. Both the House and Senate Armed Services committees had passed separate NDAAs that included provisions making it easier for military families to access IVF treatment. However, House and Senate negotiators couldn't reach agreement on "sufficient pro-life protections," the speaker's office said.

"The Speaker remains pro-IVF and has encouraged states to take up the issue responsibly and ethically," a Johnson spokesman said.

Despite representing a broad constituency of military families in San Diego, Rep. Sara Jacobs was among the Democrats who voted against the NDAA.

"Unfortunately, because Speaker Johnson added these poison pills, I am forced to vote against a bill that I would otherwise happily have supported," Jacobs told NBC News, referencing the ban on gender-affirming care.

Jacobs said there are "thousands" of families that the policy would impact. "I get lots of phone calls from service members … they care about the fact that they can't find childcare, that their housing is inadequate, that they're having to go to the food bank," Jacobs added.

No calls, she said, are about culture war issues, like "whether they're going to drag shows."

The progressive Democrat and member of leadership also worked across the chamber, and across the aisle, to insert language in the package that would have provided an expansion of coverage of fertility treatments, including IVF, to servicemembers. 

Johnson stripped the provision out of the bill, Jacobs said, because "there were some people in his caucus who were uncomfortable with it."

"The military is having a recruitment and retention problem," she continued. "And the idea that we would not be giving them [access to IVF] that is going to be a standard across the federal workforce, to me, makes no sense."