Write a constitutional amendment changing a President's term to six years instead of four, with no reelection.

Elections with a sitting President on the ballot are more divisive and intense than ones with no incumbent. Not only that, historically we tend to re-elect the incumbent anyway. This avoids all the trouble.

The terms of Senators could be shortened to four years so that there aren't some Senate seats that always coincide with a Presidential election. There should still be a rotation.