He hasn't even nominated hundreds. That's not the fault of the democrats.
Just shy of 200 last count, and I agree, this is something that needs to be taken care of. The White House should be nominating them, and it is one of the things Congress should be making a priority of while they are hiding behind the smokescreen of on again, off again, repeal/replacement of Obamacare, when the writing on the wall says that neither of those is going to happen.
No machine can function efficiently while missing parts, and holdover staff tend to be loyal to those who gave them their jobs in the first place.