Democrats have a problem with messaging, or at least in recent years we do. As I've argued elsewhere, FDR was a genius at messaging and we need to recapture his talents.
In this case, the message that we should use is simple: "Do your job."
There is no need to explain all the technicalities. The basic voter understands that Congress is not working. Whenever a Dem is challenged their answer should be simple:
Look, it's very simple. We work for the American people and our job is to keep their government running. Not some of their government some of the time. Not the parts of the government that my colleagues on the other side personally like or are too cowardly to oppose, ALL of the government. All of it. We work for ALL of the people. We have been trying very hard to do right by those people, ALL of those people. But, my GOP colleagues have been more interested in cheap political posturing. So to them I say this: Do your job. Do your job, like we're trying to do ours. Do your job like hundreds of thousands of federal employees are doing theirs without pay, while you fail to do yours and keep your pay. Do your job so that the other hundreds of thousands of federal employees, that you are forcing to stay out of work can do their jobs. No more posturing. No more bullshit. Earn your pay. Do your job, already. Just do your job.
Stay on message: The House GOP is not doing its job. They have to do their jobs so that we, and everyone else in the government can do theirs, and get properly paid for it. They need to do their jobs.
If enough Dems and Dem operatives hammer this idea home, then it will begin to catch on.
Ideally, it will reach some of those very angry federal workers with a whole lot of time on their hands. I don't know what the rules are for federal employees and political speech, but whatever they are, I can tell you this: they don't apply to their families.
Imagine if the House GOP leadership were flooded with emails saying "I just want the Republicans do their jobs so that my [fill in the blank] can do his/hers."
Get all of those people who can't go to the national parks a simple message that they can deliver to the GOP:
Do your job.
Do your job.
Just shut up, already, and do your job.