In the spirit of ELI5 I'm going to give this an old school shot:
You see, a large part of the people in in this country have somehow convinced themselves that helping poor people is a bad thing. I'm not sure how that happened. When I was growing up helping poor people was a good thing. It's even in the Bible that you're supposed to help poor people.
The people who think that helping poor people is a bad thing feel very strongly about it and voted really, really hard. They voted harder than the people that think helping poor people is a good thing, and they voted waaaaay harder than the people who most likely think that helping poor people is a good thing but didn't vote for whatever reason.
The politicians who got elected by the people who think helping poor people is a good thing (Democrats) don't have much power right now, but the politicians who got elected by the people who think helping poor people is a bad thing (Republicans) still need the Democrats participation to run the government. The Democrats have refused to help the Republicans when the Republicans are actively trying to take away help for poor people.
So it is the Democrats "fault" for not participating when the Republicans intend to take away help for poor people. But the Republicans are in control and could easily just, you know, continue helping poor people.
Really it's everybody's fault for letting people who think helping poor people is a bad thing become so powerful that they now run the country. We could do better.