Term Limits for Congress

Support for term limits is very high across the political spectrum, as explained in this article which provides interesting history.

Although I’m not strongly opposed to term limits, it concerns me that term limits would keep voters from being able to be served by outstanding legislators for a long time.  I'd prefer to increase the margin that a candidate needs to win by, depending on how many terms (s)he has had.  Someone who has had [2] terms might need to get [51%] of the vote to win; someone who has had [3] terms might need [52%] to win.  Statistical analysis could help set those requirements.  The idea is to (partly) offset the advantage of being an incumbent.  A truly outstanding servant could still win.

Because it would be harder to keep winning term-after-term, politicians would be less likely to keep running, and political parties would be more likely to prefer a new candidate.

My idea seems impossible to achieve.  It would be opposed for various reasons.  Many people would consider it undemocratic to allow someone getting fewer votes to be declared the winner.  Others would interpret such an approach to make some votes worth more than others.

Because my idea seems impossible, I would not oppose term limits.  

It is very unclear, however, who would be interested in running for office with term limits.  For professionals, being in Congress could be very disruptive to their career earnings unless they leverage their political position (which we really don’t want them to do).  People in careers that don't have advancement paths would be more inclined to run.  People who own businesses that can be run by others would find it easier to run.  Teachers (especially history or political science teachers) might be interested although they would lose seniority.

I am strongly in favor of Ranked-Choice Voting which I think would make it harder for candidates to get re-elected repeatedly.