AFAIK, Dan Goldin once ordered calculations for return to the Moon on the cheap. The bottom price was about $1B to bring humans to the Moon surface again (and s

AFAIK, Dan Goldin once ordered calculations for return to the Moon on the cheap. The bottom price was about $1B to bring humans to the Moon surface again (and safely return them back) using then-dirt-cheap Proton launchers. Congress could apply its force in a few different ways here. For one Congress may decide not to spend on the Moon program because it's too expensive. For comparison the NASA annual budget is about $20B, so the Moon has to be expensive related to that. For another Congress may insist to use pretty expensive but politically convenient means, like SLS, for that. Big total budget will require delays, so the program will move slowly.