Oh I agree the majority vote D. I work with a lot of them.
I think he's hoping this will put pressure on the D's to cave. But I promise you the asshats I work with who vote D will never vote R.
Instead, though, my anecdotal "boots on the ground" take is many of my R and I coworkers are disgruntled with Trump and would vote for a moderate D over him in a heartbeat at this point.
Trump's not my favorite CinC, but it's pretty clear that a bunch of American's want stronger border security, and a wall, Trump was elected in a large part on a promise to build a wall, and he said for the better part of a year that he would not sign a spending bill that didn't include funding for that promise.
Congress had almost two years to figure out how to give funding for that project, that again, a large portion of Americans elected representatives to do, or gather enough votes to override the President's veto power. Congressional leaders could do neither. In fact, as far as I can tell, Trump hasn't actually vetoed anything as Congress can't even get a bill through both houses.
This issue is Congress's fault, and blaming Trump for actually keeping his word, even if you disagree with it, is incorrect IMO.