"NASA has selected a launch vehicle architecture that includes a large cryogenic (LOX/LH2) Core Stage, an Upper Stage when needed for higher performance missions, high thrust Boosters (initially, using those developed for the Ares I vehicle) for liftoff thrust, using either 3, 4, or 5 RS-25 engines on Core Stage, and using 1, 2, or 3 J-2X engines on Upper Stage. While the launch vehicle configuration will change based upon mission needs for lift performance, the basic design of the Stages will be the same for all missions, with the only change being how many engines will be mounted in the Main Propulsion System of the Core Stage (or Upper Stage) for a given mission. ... The Government does not intend to acquire a commercial item using FAR Part 12."
"NASA/MSFC intends to negotiate only with Pratt & Whitney Rocketdyne (PWR) for the SLS Core Stage Engines. This decision is made pursuant to FAR 6.302-1, only one responsible source and no other supplies or services will satisfy agency requirements, which implements the authority for 10 U.S.C. 2304(c)(1). ... The Government does not intend to acquire a commercial item using FAR Part 12."
"I have serious concerns with NASA's attempt to avoid holding a full and open competition to acquire the SLS. Instead, NASA is considering modifying and/or extending existing contracts for retired or cancelled programs resulting in one or more "de facto sole source awards."
"In a press conference, William Gerstenmaier, associate administrator for NASA's Human Exploration and Operations said that the first stage will be designed from the onset to accept a variety or range of strap-on boosters. When asked when that procurement will begin, Gerstenmaier said that this "wIll begin almost immediately - competition begins as soon as we go do this [procurement] activity."
Keith's note: Despite statements by HEOMD AA Bill Gerstenmaier there is little if any evidence that there is any true interest on NASA's part to begin competitive procurement on the SLS any time soon.