It's kind of stating the obvious but a national election is for who is to run the country, not a support base. The latter is what the primaries are for.
That means he will have to address, and represent, the best interests of the country as a whole, including in a lot of areas that he didn't even take a position on while campaigning -- but what he does absolutely *MUST* be done in the greater interests of the country, whether a given action synchs with his campaign rhetoric or not. Once the election is decided, the pandering is over.
That's exactly why the first thing we do, literally at the moment he gets the job, is to make him swear to "preserve, protect and defend the Constitution". Not to "preserve, protect and defend those who voted for him" and not to "preserve, protect and defend a political party or ideology". That would be absurd.
In the same way, if we all decide we need to drive to Denver and 310 million of us get into a car, those in the back seat may or may not agree with what routes the driver takes or how he drives. But he damn well better get us there.