I think their is fatigue everywhere, democrat, republican, insider, outsider...republicans are screwing themselves out of the presidency probably for a few more terms minimum by not holding more moderate positions on social issues, alienating minorities, and continually voting for crazies at the state and national level. They have no one to blame but themselves.
Let me break this down a bit:
Moderate positions on social issues: Well being for "Immigration Reform" comes to mind.
Alienting Minorities: Trump's rhetoric about Mexicans is totally unacceptable.
Voting for Crazies at the National and State Level: Well Republicans aren't having problems getting in people voted in at the State Level or at the Congressional Level. Its the Presidency as you have put it that they have put themselves out of of late.
Yes, true, my point was more that some of the republicans that are getting elected are ruining the party name as a whole. I'm thinking of some past comments about race, rape, etc. A lot of people probably don't remember who specifically said what, but some comments have likely made impacts on some regarding their view of the party. The extreme few on the right, regardless their level of office, are driving the mainstream view of the party.