He did indeed have a Rolodex of names he could have called. But the unprecedented Democrat terrorism made almost all of them refuse to get involved in the administration. The attacks in restaurants, the guaranteed over the top colonoscopy about their life, instant crimibal investigations into who they were.
Democrat extremism supported by Republicans who expected him to be proven as a Russian spy made it impossible for him to get the staff he wanted. There is no telling the damage Paul Ryan and Mitchell did to the country while they shrunk back from the Democrat lie.
Fortunately, Trump is and was smart enough to know that he needed Mitch McConnell on his side to get Neil Gorsuch and Brett Kavanaugh in place, as well as many other conservative judges throughout the courts. Trump plays to win in the end.