On a FB comment thread about the shutdown, one David Burkhead provides a succinct answer to the accusation that the efforts of the Republican House to avoid funding the ACA are "unconstitutional":
Let me be perfectly clear. When the House of Representative says "this is what we will fund and this is what we won't" they are not engaging in dirty tricks. They are not trying to do an end-run around the Constitution. They are _using_ the authority given to them _by_ the Constitution to do. their. job.
Their ability to say "no, we won't fund that" is a feature, not a bug. It's one of the "checks and balances" built into the Constitution.