Lawmakers across Capitol Hill are fighting against the Trump administration’s shift of nearly $4 billion in procurement funding to fund new border wall construction, with multiple defense-oriented Republican members citing executive branch overreach as the main factor.

House Armed Services Committee (HASC) leaders Chairman Adam Smith (D-Wash.) and Ranking Member Mac Thornberry (R-Texas) made explicit their disapproval of the Pentagon’s shift of $3.8 billion from appropriated fiscal year 2020 funds meant to buy military aircraft, ships and trucks to instead build a wall along the U.S.-Mexico border, during a Feb. 26 posture hearing with Pentagon leaders.

Smith emphasized that his opposition to the reprogramming was not political in nature, but out of concern for congressional authority to authorize and appropriate military funds, and warned that it sent mixed signals about the department’s funding needs.

“Also, the message it sends is that the Pentagon has got plenty of money,” he noted. “We just got this long list from the services of their, quote, unfunded requirements, … and at the same time, [the department] found $3.8 billion just sitting in a corner that could go to a purpose that was not intended.

“It undercuts any argument about the need for resources within the Department of Defense,” Smith continued.

Thornberry, who has announced his plans to retire in 2020, also critiqued the reprogramming effort, which Pentagon spokespeople have previously told reporters already took place.

He noted that authorizing and appropriating lawmakers have made “different judgment calls” from the Pentagon’s annual budget request for years. While they don’t always get it right, “to me, … it is the constitutional issue.”

Thornberry emphasized that he supports the border wall effort. “But I am deeply concerned about where we’re headed with the constitutional issue about Congress’ role in national defense, and whether that is being overridden.”

The HASC leaders’ remarks follow a letter they sent Tuesday to the Pentagon’s acting comptroller, Elaine McCusker. Defense News reported Wednesday that Smith and Thornberry denied the reprogramming action in their letter and warned that the Defense Department risked losing flexibility that lawmakers have historically provided them to manage its own resources.

Several other HASC Republicans voiced their own concern regarding the reprogramming, making clear that their disapproval stemmed from what they considered an overreach by the Trump administration into Congress’ responsibility and authority to decide funding levels, rather than opposition to the border wall issue.

Rep. Liz Cheney (R-Wyo.) said at the HASC hearing that she echoed “the concerns and the comments … about the reprogramming,” and asked the Pentagon leaders whether they still agreed with a widely touted statistic that the Department required 3 percent to 5 percent of real growth annually to fund the missions outlined in the National Defense Strategy. Defense Secretary Mark Esper confirmed that was the case.

Rep. Trent Kelly (R-Miss.), who serves as a brigadier general in the Mississippi Army National Guard and is the ranking member of the HASC military personnel subcommittee, also voiced his concerns during the hearing.

“I’m supportive of the president’s policy on the border, but we have to be careful about how we reprogram,” he said, highlighting that the cuts caused by the reprogramming disproportionately affects the National Guard.

“That is alarming to me, because if we’re relying on 40 percent of our force to be able to fight tomorrow … what we’re doing is taking away the ability for them to keep pace with our active component counterparts with equipment,” Kelly said.

“That’s not what we’ve seen, and if we’re being forced to choose between modernizing our nuclear forces and building Virginia-class submarines, then you’re not asking for enough money and we’re not providing you with the kind of regularity that you need,” Cheney said.

Senators also made clear their opposition to the reprogramming effort this week. Sen. Dick Durbin (D-Ill.) introduced a bill on Wednesday that would “reverse and restore” military funding. Durbin is the ranking member of the Senate Appropriations Defense Subcommittee, and his bill was co-sponsored by SAC Ranking Member Patrick Leahy (D-Vt.), Senate Armed Services Committee (SASC) Ranking Member Jack Reed (D-R.I.), Senate Appropriations Military Construction and Veterans Affairs Subcommittee Ranking Member Brian Schatz (D-Hawaii), and 28 additional senators.

“Every dollar diverted from our men and women in uniform for President Trump’s ‘big, beautiful’ border wall was appropriated by Congress to address a need identified by our military,” Durbin said in a Wednesday release announcing the bill. “This latest reprogramming was not just an attack on Congress’ power of the purse, it was an attack on military readiness. The Senate should reject the President’s money grab and reassert our Constitutionally-granted powers by supporting this legislation.”

Seven Democratic members of the SASC committee co-signed the bill, including Reed. Two Democratic presidential candidates – Sens. Bernie Sanders (I-Vt.) and Amy Klobuchar (D-Minn.) – also cosponsored the bill. Sen. Elizabeth Warren (D-Mass.), a member of SASC and a Democratic presidential candidate, did not cosponsor the bill.