We really need a minimum approval rating or term limits for all.
Under the approval ratings, their pay would be linked to their ratings - the higher percentage their rating is, the more pay they get. If their rating is 80%, then they get 80% of their pay. Also, to this, should the ratings fall below... lets say, 40%, the their state would be allowed to automatically recall their represenatives and replace them with someone else.
Or for term limits, add term limits to congress and the senate like the presdiental seat has. To this, the limits would 4 and the presidental seat raised to that. However, they would count with each other - You serve three terms in congress/senate and one term as president and you can no longer run for either of those offices. Or one term congress/senate, three terms president. After that you can't run again. Additionally, in order to run for president, you'd have to have served at least one term in the congress/senate.
Or even better - use both plan.
Tied to approval ratings, no. It shouldn't be a popularity contest. The right thing isn't always the most popular thing.