Senate lawmakers are taking up their version of the annual defense policy bill, less than a week after their colleagues in the House pushed through a highly controversial and partisan version of the must-pass legislation.

The Senate must reconcile its fiscal 2024 National Defense Authorization Act (NDAA) with the House’s by the end of September before moving the bill to President Biden’s desk for signature. Senators intend to start negotiating with the House by the end of the month. 

But the gap between the two chambers appears to be a wide one.

The version that passed the House on Friday included dozens of hot-button amendments restricting abortion access for troops, Pentagon diversity programs and medical care for transgender service members. The amendments made the bill unpalatable to Democrats, and the traditionally bipartisan legislation squeaked through in an almost party-line vote.

The Senate’s rules mean its version will necessarily be less partisan, but Republicans are still expected to try to slip in some of the same conservative measures during floor debate.

That expectation had Majority Leader Chuck Schumer (D-N.Y.) pressing both parties Tuesday to work together and rebuff amendments to the bill that could make it unpassable. 

“I certainly hope we do not see the kind of controversy that severely hindered the NDAA process over in the House,” Schumer said on the Senate floor. “Both sides should defeat potentially toxic amendments and refrain from delaying the NDAA’s passage. So far, we have thankfully avoided all of that.”  

Schumer noted a couple of highlights that made it into the first manager’s package, including amendments to take early steps on artificial intelligence, tackle U.S. competitiveness with China and sanction China for its role in producing fentanyl. 

The Senate bill made it through its first hurdle when it passed a procedural vote 72-25 on Tuesday evening; 22 of the ‘nay’ votes were by Republicans. 

And senators Wednesday began to insert a package of 51 uncontroversial amendments to the NDAA — including 21 Republican, 21 Democratic and 9 bipartisan amendments. The upper chamber kicked off those amendment votes Wednesday afternoon.

Lawmakers are also working on a smaller manager’s package to include a number of other amendments, but have indicated they are unsure how big it will be all told.

“That’s still very much TBD,” said Sen. Tim Kaine (D-Va.), a member of the Senate Armed Services Committee. “The good news is a lot of issues are still on the table and we’re trying to work them out.”

As that process happens, Schumer and Minority Leader Mitch McConnell (R-Ky.) will attempt to hammer out an agreement for votes on more controversial proposals, a process that will largely happen behind closed doors.

“We’re discussing the amendment strategy on a regular basis,” Sen. John Thune (S.D.), the No. 2 Senate Republican, told reporters. “We’ve got some amendments that are queued up to be voted on — hopefully — already, and there will be more to come. But what exact amendments ultimately get voted on are still a consideration.”

Sen. Roger Wicker (R-Miss.), the top Republican on the chamber’s Armed Services Committee, added that there are a “number of burden-sharing votes” that Republican senators are hopeful to win amendment votes for as part of the NDAA process.

“Clearly, there are some Ukraine votes that may or may not win majorities, but members deserve to be heard on them,” Wicker said. 

One topic likely to come up, however, is the fight over the Pentagon’s policy to reimburse travel costs for service members who cross state lines to seek abortions. Sen. Tommy Tuberville (R-Ala.) since March has held up hundreds of military promotions — including numerous top roles, such as Marine Corps commandant — to force a reversal on the policy. 

While Republicans don’t have the 60 votes needed to undo the policy using the NDAA, the GOP may still push for a vote. 

Tuberville maintained Tuesday that an NDAA amendment vote would still not be enough for him to drop his hold. The Alabama Republican on Tuesday spoke with Defense Secretary Lloyd Austin for the second time in as many weeks about his months-long hold, which is approaching 300 promotions.

Pentagon officials also held a briefing on the new abortion policy for senators on the Armed Services panel early Wednesday. Tuberville told reporters that he was supportive of the language that made it into the House’s version of the bill that would roll back the Pentagon’s policy but was worried that the Senate will do away with it. 

He also said Wednesday’s briefing was not helpful and that he did not learn much, including how many military members have taken advantage of the updated policy. 

Other initiatives possibly up for votes include those that seek to curtail Pentagon diversity, equity and inclusion (DEI) efforts, cut Ukraine aid, or increase oversight for the assistance to Kyiv.

Several conservative policy wins already inserted into the Senate defense bill include language that stops the Pentagon from creating DEI-related jobs or filling vacancies for such roles until the Government Accountability Office holds a review of the Defense Department’s workforce.

Republican senators also want the Pentagon to come up with a plan to counter drug and human trafficking along the southern border.

The White House has so far declined to comment on the Senate bill, releasing a statement Tuesday noting that it is “not presenting detailed views at this time” given the legislation’s short timeframe between the public release of the bill and Senate action. 

But some lawmakers have given their prediction as to the fate of the bill, should controversial measures make their way into the Senate NDAA as it did in the House’s, including Senate Armed Services Chairman Jack Reed (D-R.I.). Reed said it “would be very challenging” to support such legislation if it hampers abortion access and diversity initiatives.

“We will have votes on many of these topics. I don’t think the Senate will support the legislation that’s been promulgated by the House,” Reed said over the weekend on CNN. “I think it just does not serve the welfare of troops, nor the professionalism and the training of the forces we need.”

Still, McConnell predicted Wednesday that the NDAA will “pass on a pretty strong bipartisan basis” after the amendment process wraps.