The Koch brothers are first and foremost libertarians, not so much conservatives, and The Donald is really neither one. This is not to defend or denigrate the Koch brothers, as they do yeoman work at the legislative level, and they occupy some of the oddest real estate in the world - they live in the minds of liberals rent-free. Just listen to some of the things that Harry Reid has said of them in the past. Harry really cannot think about much else.
——they do yeoman work at the legislative level,——
That apparently is where their current support is directed.
Support funds are finite and the current support is directed to the congressional races.
RE: “Kochs live rent free in liberals minds” ...A liberal cousin of mine mentioned the “Koch” brothers, derisively of course. I asked her if she knew of George Soros...she did not. Aaaggghhh.