Good point on the life span thing.  I favor a system where the pol is limited to one term but is allowed to run for office after sitting out  a period equal to the number of years of the term just completed. That way, during the term there are no distractions of future campaigns, influence from donors diminished, and pressure from the party is reduced.  During the term, the incumbent has nothing else to do but work to accomplish what was promised.  At least that's the way I see it.