I think President Trump is wise to do it by cities, and NOT by counties and states, especially states. He knows he has huge support in the outlying red counties of states. I thank him for not tossing us under the bus.
It is well within his Executive Powers to defund Democrat cities and even Democrat states. If he were just to defund Democrat cities, those Democrat states could still aid those cities. Presidential powers should not be used in a haphazard manner. Defund then all until they comply with the Administration.