The next-generation rocket wars continued Monday on Capitol Hill as 20 bipartisan members of the House of Representatives wrote Defense Secretary James Mattis advocating for total launch system funding as opposed to piecemeal funding.

“We write to you in support of the Air Force’s request and focus on the end goal of complete, robust launch systems,” the lawmakers wrote in a letter obtained by Defense Daily. “Critical funding should not be restricted to specific components, such as a first-stage engine.” CAPITOL

Just weeks earlier, House Armed Services Committee (HASC) Chairman Rep. Mac Thornberry (R-Texas) and HASC strategic forces subcommittee Chairman Rep. Michael Rogers (R-Ala.) wrote Air Force acting Secretary Lisa Disbrow and Pentagon acting Under Secretary of Defense for Acquisition, Technology and Logistics (AT&L) James MacStravic directing the Air Force to not obligate or expend any additional funding to ULA, other than for the launch of current Atlas and Delta rockets, until the company provides the federal government full access to, oversight of, and approval rights over decision making about any downselect on Vulcan (assuming it requests funding).

Thornberry, for his part, later walked back his part of the letter, saying he cares more about assured access to space and that it’s not up to him or the federal government to make those sort of subcontract decisions (Defense Daily, March 22). The letter also asked for congressional oversight, access to and approval of any decision to fund Vulcan.

The letter is a boost for both ULA and Blue Origin, who want to prevent Congress from meddling in ULA’s Vulcan downselect as ULA is considering a Blue Origin engine for Vulcan. Powerful lawmakers, led by Rogers, insist on a RD-180 engine replacement, ostensibly Aerojet Rocketdyne’s [AJRD] AR1 engine, which is being designed for both Vulcan and to replace the RD-180 on ULA’s Atlas V. Rogers didn’t respond to a request for comment Thursday. The letter could be considered a setback for Aerojet Rocketdyne as both the HASC chairman and ranking member have said they won’t back the RD-180 replacement approach.

The Air Force, in its budget for fiscal year 2017, requested $1.2 billion across five years to invest in domestic launch systems. The Pentagon is operating under a continuing resolution from FY 2016, which continues that fiscal years’ funding levels. The CR lasts through the end of April.

The following lawmakers signed the letter: Will Hurd (R-Texas), Pete Sessions (R-Texas), Steve Chabot (R-Ohio), Robert Bishop (R-Utah), Cathy McMorris-Rogers (R-Wash.), Doug Lamborn (R-Colo.), Chuck Fleischmann (R-Tenn.), Daniel Webster (R-Fla.), Ken Buck (R-Colo.), Carlos Curbelo (R-Fla.) and Mike Gallagher (R-Wisc.).

Though he didn’t sign the letter, Rep. Mo Brooks (R-Ala.) supports funding both total system and rocket components. Brooks spokeswoman  Annalyse Kelly said Thursday the congressman is working the issue through different means and that, specifically, he is working directly with Thornberry and HASC staff. ULA makes rockets in Brooks’ district while Aerojet Rocketdyne’s current facility is based there, according to Aerojet Rocketdyne spokeswoman Lynn Machon. Machon said Aerojet Rocketdyne’s new manufacturing facility, set to open in mid 2019, will be based in Brooks’ district, which covers much of northern Alabama, including Decatur and Huntsville.

ULA is a joint venture of Lockheed Martin [LMT] and Boeing [BA].