The proposed Republican budget: here is the problem. Or, in graphical form:
Apparently the Democrats have agreed to $38 billion of spending cuts (more than before), but the Republicans are now insisting on a rider that defunds Planned Parenthood, which the Democrats (rightly) will not agree to. Planned Parenthood provides lots of services including birth control (which, hey! reduces the number of abortions), and government money isn’t used to fund abortions per the Hyde amendment. So, yeah. This is what the government of the US is going to shut down over. Whee.