A good rule for the GOP would be that if you are a politician from a state that has not voted Republican in at least two of the last four presidential elections, you are disqualified from running as a presidential candidate. If you can’t help deliver your own state, your chances of running well nationwide are too slim.
A better rule would be to simply line up primaries in order of GOP support in the general election. So if a state goes Republican in the general election its primary is moved up to an earlier date, whereas a state (like MA or NY) that never elects a Republican president is moved down on the list. This would help insure that only Republicans are nominating the Republican candidate.