I would exclude SpaceX from the bid, but Sierra Space is the obvious other option with their Dream Chaser. Apart from Sierra and ULA there is also everyone who

I would exclude SpaceX from the bid, but Sierra Space is the obvious other option with their Dream Chaser. Apart from Sierra and ULA there is also everyone who bid on the lunar lander, meaning Dynetics and the "National Team" (Blue Origin, Northrop Grumman and Lockheed Martin)