WASHINGTON – The House Armed Services Committee is set to take up an authorization bill this week that would insist the Pentagon invest in a new main stage engine — not an upper stage engine, strap-on motors or launch vehicles as the Air Force has planned — as the cornerstone of its effort to wean itself from the Russian RD-180 rocket engine.

The proposed restrictions essentially would forbid the Air Force from funding several recently announced co-investment deals with Orbital ATK, SpaceX and United Launch Alliance beyond this year. The Air Force doled out $317 million worth of contracts to help fund Orbital ATK’s development of a new solid-fueled launcher, SpaceX’s development a new upper-stage engine, and ULA’s development of Vulcan, a potentially reusable successor to the RD-180 powered Atlas 5 rocket.

The Air Force’s only other partnership is with Aerojet Rocketdyne, which stands to receive up to $536 million to develop AR-1, a kerosene-fuled engine that the Sacramento, California-company is pitching as an RD-180 replacement that would also be suitable for Vulcan if ULA drops plans to use Blue Origin’s methane-fueled BE-4 engine instead.

The proposed funding restrictions are part of the House Armed Services Committee’s version of the National Defense Authorization Act for 2017, which will be released April 25 ahead of a planned April 27 session to amend and vote on the bill.

Rep. Mac Thornberry (R-Texas.), the committee chairman, and Rep. Mike Rogers (R-Ala.), the chairman of the strategic forces subcommittee, have traded a series of letters with Air Force leaders this year explaining their preference for a so-called engine-only approach to end reliance on the RD-180.

The Air Force relies on the RD-180 engines ULA imports from Russia’s NPO Energomash through Florida-based RD AMROSS to launch the lion’s share of U.S. national security satellites. Following Russia’s 2014 annexation of Ukraine’s Crimea region, a chorus of U.S. lawmakers and senior Pentagon officials have been calling for ending use of the RD-180. But figuring out exactly how and when to make the transition away from an RD-180-powered Atlas 5 has been a repeated point of contention.

“The Committee shares the concern of many members that reliance on Russian-designed rocket engines is no longer acceptable,” the committee said April 25. “The Chairman’s Proposal, as recommended by Chairman Rogers of the Subcommittee on Strategic Forces, denies the Air Force’s request to pursue the development, at taxpayer expense, of new commercial launch systems. It instead focuses on the development of a new American engine to replace the Russian RD-180 by 2019 to protect assured access to space and to end reliance on Russian engines. The Mark also holds the Air Force accountable for its awards of rocket propulsion contracts that violated the FY15 and FY16 NDAAs.”

In its budget request for fiscal year 2017, the Air Force said it plans to spend $1.2 billion over the next five years, including $296 million in 2017, on what they described as a next-generation launch system. Their plan calls for investing in upgrades to existing rockets or investing in entirely new systems from domestic launch providers including SpaceX, Orbital ATK and ULA.

But Rogers has repeatedly said the Air Force’s plan violates the 2015 National Defense Authorization Act by focusing on new launch systems instead of developing a domestic alternative to the RD-180.

“The funds would not be authorized to be obligated or expended to develop or procure a launch vehicle, an upper stage, a strap-on motor, or related infrastructure,” says a draft of the 2017 defense authorization bill. Industry officials expect several launch-related amendments to come up when the full committee meets to markup the bill April 27,

The bill, as drafted, would leave Aerojet Rocketdyne’s AR1 engine as the only piece of the Air Force’s portfolio of rocket-propulsion partnerships that meets the new criteria. The proposed restrictions would also require any unobligated money from 2015 or 2016 follow the same guidelines.